Method for manufacturing semiconductor device, substrate-processing apparatus, and recording medium

ABSTRACT

There is provided a method for manufacturing a semiconductor device, including: providing a substrate with an oxide film formed on a surface thereof; pre-processing a surface of the oxide film; and forming a nitride film containing carbon on the surface of the oxide film which has been pre-processed, by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: supplying a precursor gas to the substrate; supplying a carbon-containing gas to the substrate; and supplying a nitrogen-containing gas to the substrate, or by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: supplying a precursor gas to the substrate; and supplying a gas containing carbon and nitrogen to the substrate, or by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: supplying a precursor gas containing carbon to the substrate; and supplying a nitrogen-containing gas to the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.15/386,859, filed Dec. 21, 2016, which is a Continuation Application ofPCT International Application No. PCT/JP2015/068132, filed Jun. 24,2015, which claimed the benefit of Japanese Patent Application No.2014-130267, filed Jun. 25, 2014, the entire contents of which areincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a method for manufacturing asemiconductor device, a substrate-processing apparatus, and anon-transitory computer-readable recording medium.

BACKGROUND

As one process for manufacturing a semiconductor device, a process offorming a nitride film, such as a silicon nitride film (Si₃N₄ film,hereinafter, also referred to as an SiN film) or the like as aprotective film on a substrate on which an oxide film such as a siliconoxide film (SiO₂ film, hereinafter, also referred to as an SiO film) orthe like is formed, is often performed. When an etching process isperformed on the substrate, the oxide film can be protected by thenitride film formed on the oxide film.

However, if a film thickness of the nitride film is thin, the functionof the nitride film as the protective film may be lowered. As a result,when an etching process is performed on the substrate, the oxide filmmay be damaged. The present disclosure provides some embodiments of atechnique capable of suppressing a degradation of a function of anitride film as a protective film.

SUMMARY

According to one embodiment of the present disclosure, there is provideda technology which includes: providing a substrate with an oxide filmformed on a surface thereof; pre-processing a surface of the oxide film;and forming a nitride film containing carbon on the surface of the oxidefilm which has been pre-processed, by performing a cycle a predeterminednumber of times, the cycle including non-simultaneously performing:supplying a precursor gas to the substrate; supplying acarbon-containing gas to the substrate; and supplying anitrogen-containing gas to the substrate, or by performing a cycle apredetermined number of times, the cycle including non-simultaneouslyperforming: supplying a precursor gas to the substrate; and supplying agas containing carbon and nitrogen to the substrate, or by performing acycle a predetermined number of times, the cycle includingnon-simultaneously performing: supplying a precursor gas containingcarbon to the substrate; and supplying a nitrogen-containing gas to thesubstrate.

According to some embodiments of the present disclosure, it is possibleto suppress a degradation of a function of a nitride film as aprotective film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of a vertical type processfurnace of a substrate-processing apparatus suitably used in anembodiment of the present disclosure, in which a portion of the processfurnace is shown in a vertical cross sectional view.

FIG. 2 is a schematic configuration diagram of a portion of the verticaltype process furnace of the substrate-processing apparatus suitably usedin the embodiment of the present disclosure, in which a portion of theprocess furnace is shown in a cross sectional view taken along line A-Ain FIG. 1.

FIG. 3 is a schematic configuration diagram of a controller of thesubstrate-processing apparatus suitably used in the embodiment of thepresent disclosure, in which a control system of the controller is shownin a block diagram.

FIG. 4 is a diagram illustrating a gas supply timing in a film formingsequence according to one embodiment of the present disclosure.

FIG. 5 is a diagram illustrating a modification of the gas supply timingin the film forming sequence of one embodiment of the presentdisclosure.

FIG. 6 is a diagram illustrating a modification of the gas supply timingin the film forming sequence of one embodiment of the presentdisclosure.

FIG. 7 is a diagram illustrating a modification of the gas supply timingin the film forming sequence of one embodiment of the presentdisclosure.

FIG. 8 is a diagram illustrating a modification of the gas supply timingin the film forming sequence of one embodiment of the presentdisclosure.

FIG. 9 is a view illustrating a cross sectional structure of a filmformed on a substrate.

FIG. 10 is a view illustrating a cross sectional structure of a filmformed on a substrate.

FIG. 11 is a view illustrating a cross sectional structure of a filmformed on a substrate.

FIG. 12 is a view illustrating a cross sectional structure of a filmformed on a substrate.

FIG. 13A is a view illustrating a cross sectional structure of asubstrate to be processed, FIG. 13B is a view illustrating a crosssectional structure of a substrate after a film forming process, andFIG. 13C is a view illustrating a cross sectional structure of asubstrate after a heating process.

FIG. 14A is a view illustrating an evaluation result of etchingtolerance in an Example, and FIG. 14B is a view illustrating anevaluation result of etching tolerance in a Comparative example.

FIG. 15 is a schematic configuration diagram of a process furnace of asubstrate-processing apparatus suitably used in another embodiment ofthe present disclosure, in which the portion of the process furnace isshown in a vertical cross sectional view.

FIG. 16 is a schematic configuration diagram of a process furnace of asubstrate-processing apparatus suitably used in another embodiment ofthe present disclosure, in which the portion of the process furnace isshown in a vertical cross sectional view.

DETAILED DESCRIPTION First Embodiment

A first embodiment of the present disclosure will be now describedmainly with reference to FIGS. 1 to 4.

(1) Configuration of Substrate-Processing Apparatus

First, a configuration of a substrate-processing apparatus as a firstsubstrate processing part will be described with reference to FIGS. 1 to3. As illustrated in FIG. 1, a process furnace 202 includes a heater 207as a heating mechanism (temperature adjustment part). The heater 207 hasa cylindrical shape and is supported by a heater base (not shown)serving as a holding plate so as to be vertically installed. The heater207 functions as an activation mechanism (an excitation part) configuredto activate (excite) a gas with heat, as will be described later.

A reaction tube 203 constituting a reaction vessel (process vessel) isdisposed inside the heater 207 in a concentric form along the heater207. The reaction tube 203 is made of, for example, a heat resistantmaterial such as quartz (SiO₂), silicon carbide (SiC) or the like andhas a cylindrical shape with its upper end closed and its lower endopened. A process chamber (first process chamber) 201 is formed in acylindrical hollow of the reaction tube 203. The process chamber 201 isconfigured to accommodate wafers 200 as substrates. The wafers 200 arehorizontally stacked in multiple stages to be arranged in a verticaldirection inside a boat 217 which will be described later.

Nozzles 249 a and 249 b are installed in the process chamber 201 so asto penetrate through a lower portion of the reaction tube 203. Thenozzles 249 a and 249 b are made of, for example, a heat resistantmaterial such as quartz, SiC or the like. Gas supply pipes 232 a and 232b are respectively connected to the nozzles 249 a and 249 b. A gassupply pipe 232 c is connected to the gas supply pipe 232 b. In thisway, the two nozzles 249 a and 249 b and the three gas supply pipes 232a to 232 c are installed in the reaction tube 203 such that plural kindsof gases are supplied into the process chamber 201.

However, the process furnace 202 of the present embodiment is notlimited to the aforementioned configuration. For example, a manifoldmade of metal and configured to support the reaction tube 203 may beinstalled below the reaction tube 203. Each of the nozzles may beinstalled to penetrate through a sidewall of the manifold. In this case,an exhaust pipe 231 to be described later may be further installed inthe manifold. Even in this case, the exhaust pipe 231 may be installedbelow the reaction tube 203, rather than in the manifold. In thismanner, a furnace opening portion of the process furnace 202 may be madeof metal and the nozzles or the like may be attached to the metalfurnace opening portion.

Mass flow controllers (MFCs) 241 a to 241 c as flow rate controllers(flow rate control parts), and valves 243 a to 243 c as opening/closingvalves, are sequentially installed in the gas supply pipes 232 a to 232c from the respective upstream sides, respectively. Gas supply pipes 232d and 232 e, which supply an inert gas, are respectively connected tothe gas supply pipes 232 a and 232 b at the downstream sides of thevalves 243 a and 243 b. MFCs 241 d and 241 e as flow rate controllers(flow rate control parts), and valves 243 d and 243 e as opening/closingvalves, are respectively installed in the gas supply pipes 232 d and 232e sequentially from the respective upstream sides.

The nozzle 249 a is connected to a front end portion of the gas supplypipe 232 a. As illustrated in FIG. 2, the nozzle 249 a is disposed in acircular ring-shaped space in a plan view between the inner wall of thereaction tube 203 and the wafers 200 such that the nozzle 249 a isinstalled to extend upward along a stacking direction of the wafers 200from a lower portion of the inner wall of the reaction tube 203 to anupper portion of the inner wall of the reaction tube 203. Specifically,the nozzle 249 a is installed at a lateral side of a wafer arrangementregion in which the wafers 200 are arranged, namely in a region whichhorizontally surrounds the wafer arrangement region, so as to extendalong the wafer arrangement region. That is to say, the nozzle 249 a isinstalled in a perpendicular relationship with the surfaces (flatsurfaces) of the wafers 200 at a lateral side of the end portions(peripheral edge portions) of the wafers 200 which are carried into theprocess chamber 201. The nozzle 249 a is configured as an L-shaped longnozzle. A horizontal portion of the nozzle 249 a is installed topenetrate through a sidewall of a lower portion of the reaction tube203. A vertical portion of the nozzle 249 a is installed to extendupward at least from one end portion of the wafer arrangement regiontoward the other end portion of the wafer arrangement region. Gas supplyholes 250 a through which gas is supplied are formed on the side surfaceof the nozzle 249 a. The gas supply holes 250 a are opened toward thecenter of the reaction tube 203 so as to allow a gas to be suppliedtoward the wafers 200. The gas supply holes 250 a may be formed to spanfrom the lower portion to the upper portion of the reaction tube 203.The respective gas supply holes 250 a may have the same opening area andmay be formed at the same opening pitch.

The nozzle 249 b is connected to a front end portion of the gas supplypipe 232 b. The nozzle 249 b is installed within a buffer chamber 237which is a gas diffusion space. The buffer chamber 237 is formed betweenthe inner wall of the reaction tube 203 and a partition wall 237 a. Asillustrated in FIG. 2, the buffer chamber 237 (the partition wall 237 a)is installed in a circular ring-shaped space in a plan view between theinner wall of the reaction tube 203 and the wafers 200 such that thebuffer chamber 237 (the partition wall 237 a) extends along the stackingdirection of the wafers 200 from the lower portion of the inner wall ofthe reaction tube 203 to the upper portion of the inner wall of thereaction tube 203. That is to say, the buffer chamber 237 (the partitionwall 237 a) is installed at the lateral side of the wafer arrangementregion, namely in the region which horizontally surrounds the waferarrangement region, so as to extend along the wafer arrangement region.Gas supply holes 250 c through which gas is supplied are formed in anend portion of the surface of the partition wall 237 a which faces(adjoins) the wafers 200. The gas supply holes 250 c are opened towardthe center of the reaction tube 203 such that gas is supplied toward thewafers 200. The gas supply holes 250 c may be formed to span from thelower portion to the upper portion of the reaction tube 203. The gassupply holes 250 c may have the same opening area and may be formed atthe same opening pitch.

The nozzle 249 b is installed in an end portion of the buffer chamber237 opposite to the end portion of the buffer chamber 237 having the gassupply holes 250 c such that the nozzle 249 b extends upward along thestacking direction of the wafers 200 from the lower portion of the innerwall of the reaction tube 203 to the upper portion of the inner wall ofthe reaction tube 203. Specifically, the nozzle 249 b is installed atthe lateral side of the wafer arrangement region in which the wafers 200are arranged, namely in the region which horizontally surrounds thewafer arrangement region, so as to extend along the wafer arrangementregion. That is to say, the nozzle 249 b is installed in a perpendicularrelationship with the surfaces of the wafers 200 at the lateral side ofthe end portions of the wafers 200 which are carried into the processchamber 201. The nozzle 249 b is configured as an L-shaped long nozzle.A horizontal portion of the nozzle 249 b is installed to penetratethrough the sidewall of the lower portion of the manifold 209. Avertical portion of the nozzle 249 b is installed to extend upward atleast from one end portion of the wafer arrangement region toward theother end portion of the wafer arrangement region. Gas supply holes 250b through which gas is supplied are formed in the side surface of thenozzle 249 b. The gas supply holes 250 b are opened toward the center ofthe buffer chamber 237. Similar to the gas supply holes 250 c, the gassupply holes 250 b may be formed to span from the lower portion to theupper portion of the reaction tube 203. In the case where a differentialpressure between the interior of the buffer chamber 237 and the interiorof the process chamber 201 is small, the opening area and the openingpitch of the gas supply holes 250 b may be respectively set to remainconstant between the upstream side (lower portion) and the downstreamside (upper portion) of the nozzle 249 b. In the case where thedifferential pressure between the interior of the buffer chamber 237 andthe interior of the process chamber 201 is large, the opening area ofthe gas supply holes 250 b may be set to become gradually larger fromthe upstream side toward the downstream side of the nozzle 249 b, or theopening pitch of the gas supply holes 250 b may be set to becomegradually smaller from the upstream side toward the downstream side ofthe nozzle 249 b.

By adjusting the opening area or the opening pitch of each of the gassupply holes 250 b between the upstream side and the downstream side asmentioned above, it is possible to inject a gas from the gas supplyholes 250 b at different flow velocities but at a substantially equalflow rate. The gas injected from the respective gas supply holes 250 bis first introduced into the buffer chamber 237. This makes it possibleto equalize the flow velocities of the gas within the buffer chamber237. The gas injected from the respective gas supply holes 250 b intothe buffer chamber 237 is injected from the gas supply holes 250 c intothe process chamber 201 after the particle velocity of the gas isrelaxed within the buffer chamber 237. The gas injected from therespective gas supply holes 250 b into the buffer chamber 237 has auniform flow rate and a uniform flow velocity when injected from therespective gas supply holes 250 c into the process chamber 201.

As described above, in the present embodiment, a gas is transferredthrough the nozzles 249 a and 249 b and the buffer chamber 237, whichare disposed in a lengthwise long space of a circular ring shape in aplan view, i.e., a cylindrical space, defined by the inner wall of theside wall of the reaction tube 203 and the end portions (peripheral edgeportions) of the wafers 200 carried into the reaction tube 203. The gasis initially injected into the reaction tube 203, near the wafers 200,through the gas supply holes 250 a to 250 c formed in the nozzles 249 aand 249 b and the buffer chamber 237. Accordingly, the gas supplied intothe reaction tube 203 mainly flows in the reaction tube 203 in adirection parallel to surfaces of the wafers 200, i.e., in a horizontaldirection. With this configuration, the gas can be uniformly supplied tothe respective wafers 200. This makes it possible to improve the filmthickness uniformity of a film formed on each of the wafers 200. Inaddition, the gas flowing on the surfaces of the wafers 200, i.e., theresidual gas after reaction, flows toward an exhaust port, i.e., theexhaust pipe 231 which will be described later. However, the flowdirection of the residual gas is not limited to a vertical direction butmay be appropriately decided depending on a position of the exhaustport.

A precursor gas containing a predetermined element, for example, ahalosilane precursor gas which contains silicon (Si) as a predeterminedelement and a halogen element, is supplied from the gas supply pipe 232a into the process chamber 201 through the MFC 241 a, the valve 243 a,and the nozzle 249 a.

The halosilane precursor gas refers to a gaseous halosilane precursor,for example, a gas obtained by vaporizing a halosilane precursor whichremains in a liquid state under room temperature and atmosphericpressure, or a halosilane precursor which remains in a gaseous stateunder room temperature and atmospheric pressure. The halosilaneprecursor refers to a silane precursor having a halogen group. Thehalogen group includes a chloro group, a fluoro group, a bromo group, aniodine group, and the like. That is to say, the halogen group includes ahalogen element such as chlorine (Cl), fluorine (F), bromine (Br),iodine (I) or the like. The halosilane precursor may refer to one kindof halogenide. When the term “precursor” is used herein, it may refer to“a liquid precursor staying in a liquid state,” “a precursor gas stayingin a gaseous state”, or both.

As the halosilane precursor gas, it may be possible to use a precursorgas which contains, for example, Si and Cl, i.e., a chlorosilaneprecursor gas. The chlorosilane precursor gas acts as a silicon source(Si source) in a film forming process which will be described later. Asthe chlorosilane precursor gas, it may be possible to use, for example,a dichlorosilane (SiH₂Cl₂, abbreviation: DCS) gas.

A reaction gas which has a chemical structure (molecular structure)different from that of a precursor gas, for example, a nitrogen(N)-containing gas, is supplied from the gas supply pipe 232 b into theprocess chamber 201 through the MFC 241 b, the valve 243 b, the nozzle249 b, and the buffer chamber 237. As the N-containing gas, it may bepossible to use, for example, a hydrogen nitride-based gas. The hydrogennitride-based gas may be a substance consisting of only two elements Nand H, and acts as a nitriding gas, i.e., a nitrogen source (N source),in the film forming process which will be described later. As thehydrogen nitride-based gas, it may be possible to use, for example, anammonia (NH₃) gas.

A reaction gas which has a chemical structure different from that of aprecursor gas, for example, a carbon (C)-containing gas, is suppliedfrom the gas supply pipe 232 c into the process chamber 201 through theMFC 241 c, the valve 243 c, the gas supply pipe 232 b, the nozzle 249 b,and the buffer chamber 237. As the C-containing gas, it may be possibleto use, for example, a hydrocarbon-based gas. The hydrocarbon-based gasmay be a substance consisting of only two elements C and H, and acts asa carbon source (C source), in the film forming process which will bedescribed later. As the hydrocarbon-based gas, it may be possible touse, for example, a propylene (C₃H₆) gas.

A modification gas is supplied from the gas supply pipes 232 a and 232 binto the process chamber 201 through the MFCs 241 a and 241 b, thevalves 243 a and 243 b, the nozzles 249 a and 249 b, and the bufferchamber 237.

As the modification gas, it may be possible to use an N-containing gasin a plasma-excited state. As the N-containing gas, it may be possibleto use, for example, at least one gas selected from a group consistingof an NH₃ gas, a diagen (N₂H₂) gas, a hydrazine (N₂H₄) gas, and an N₃H₈gas.

Further, as the modification gas, it may be possible to use an inert gasin a plasma-excited state. As the inert gas, it may be possible to useat least one gas selected from a group consisting of a nitrogen (N₂) gasand a rare gas. As the rare gas, it may be possible to use at least onegas selected from a group consisting of an argon (Ar) gas, a helium (He)gas, a neon (Ne) gas and a xenon (Xe) gas.

Also, as the modification gas, it may be possible to use a hydrogen(H)-containing gas in a plasma-excited state. As the H-containing gas,it may be possible to use, for example, at least one gas selected from agroup consisting of a hydrogen (H₂) gas and a heavy hydrogen (D₂) gas.

In addition, as the modification gas, it may be possible to use anoxygen (O)-containing gas in a plasma-excited state. As the O-containinggas, it may be possible to use, for example, an oxygen (O₂) gas. Also,as the modification gas, it may be possible to use, for example, anozone (O₃) gas, an O₂ gas, or an H₂ gas (O₂+H₂ gas) which stays in anon-plasma-excited state.

An inert gas, for example, an N₂ gas, is supplied from the gas supplypipes 232 d and 232 e into the process chamber 201 via the MFCs 241 dand 241 e, the valves 243 d and 243 e, the gas supply pipes 232 a and232 b, the nozzles 249 a and 249 b, and the buffer chamber 237.

A precursor gas supply system (first supply system) is mainly configuredby the gas supply pipe 232 a, the MFC 241 a, and the valve 243 a. Thenozzle 249 a may be regarded as being included in the precursor gassupply system. The precursor gas supply system may be referred to as aprecursor supply system. In the case where the halosilane precursor gasis supplied from the gas supply pipe 232 a, the precursor gas supplysystem may be referred to as a halosilane precursor gas supply system ora halosilane precursor supply system.

Further, an N-containing gas supply system (second supply system) ismainly configured by the gas supply pipe 232 b, the MFC 241 b, and thevalve 243 b. The nozzle 249 b and the buffer chamber 237 may be regardedas being included in the N-containing gas supply system. TheN-containing gas supply system may be referred to as a nitriding gassupply system or a nitriding agent supply system. In the case where ahydrogen nitride-based gas is supplied from the gas supply pipe 232 b,the N-containing gas supply system may be referred to as a hydrogennitride-based gas supply system or a hydrogen nitride supply system.

Furthermore, a C-containing gas supply system (third supply system) ismainly configured by the gas supply pipe 232 c, the MFC 241 c, and thevalve 243 c. The nozzle 249 b and the buffer chamber 237, which exist atthe downstream side of a connection portion where the gas supply pipe232 b is connected to the gas supply pipe 232 c, may be regarded asbeing included in the C-containing gas supply system. In the case wherethe hydrocarbon-based gas is supplied from the gas supply pipe 232 c,the C-containing gas supply system may be referred to as ahydrocarbon-based gas supply system or a hydrocarbon supply system.

Further, in the case where the aforementioned modification gas issupplied from the gas supply pipes 232 a and 232 b, the gas supplysystem configured by the gas supply pipe 232 a, the MFC 241 a, and thevalve 243 a or the gas supply system configured by the gas supply pipe232 b, the MFC 241 b, and the valve 243 b may be referred to as amodification gas supply system (fourth supply system). The nozzles 249 aand 249 b and the buffer chamber 237 may be regarded as being includedin the modification gas supply system.

One or both of the N-containing gas supply systems and the C-containinggas supply system as described above may be referred to as a reactiongas supply system. Further, one or all of the precursor gas, thereaction gas, and the modification gas as described above may bereferred to as a process gas. Moreover, one or all of the precursor gassupply system, the reaction gas supply system, and the modification gassupply system may be referred to as a process gas supply system and maybe simply referred to as a supply system.

Further, an inert gas supply system is mainly configured by the gassupply pipes 232 d and 232 e, the MFCs 241 d and 241 e, the valves 243 dand 243 e. The inert gas supply system may be referred to as a purge gassupply system or a carrier gas supply system.

As illustrated in FIG. 2, two rod-shaped electrodes 269 and 270 made ofa conductive material and having an elongated structure are disposedwithin the buffer chamber 237 so as to extend along the arrangementdirection of the wafers 200 from the lower portion of the reaction tube203 to the upper portion of the reaction tube 203. The respectiverod-shaped electrodes 269 and 270 are installed parallel to the nozzle249 b. Each of the rod-shaped electrodes 269 and 270 is covered with andprotected by an electrode protection tube 275 from the lower portion tothe upper portion of the rod-shaped electrodes 269 and 270. One of therod-shaped electrodes 269 and 270 is connected to a high-frequency powersource 273 via a matcher 272 and the other is grounded to the earthwhich is a reference potential. By applying radio-frequency (RF) powerfrom the high-frequency power source 273 to between the rod-shapedelectrodes 269 and 270, plasma is generated in a plasma generationregion 224 between the rod-shaped electrodes 269 and 270. A plasmasource as a plasma generator (plasma generation part) is mainlyconfigured by the rod-shaped electrodes 269 and 270 and the electrodeprotection tubes 275. The matcher 272 and the high-frequency powersource 273 may be regarded as being included in the plasma source. Aswill be described later, the plasma source functions as a plasmaexcitation part (activation mechanism) for plasma-exciting a gas, namelyexciting (or activating) a gas in a plasma state.

The electrode protection tubes 275 have a structure that enables therespective rod-shaped electrodes 269 and 270 to be inserted into thebuffer chamber 237 in a state in which the rod-shaped electrodes 269 and270 are isolated from the internal atmosphere of the buffer chamber 237.If a concentration of oxygen (O) within the electrode protection tubes275 is substantially equal to a concentration of O in the ambient air,the rod-shaped electrodes 269 and 270 respectively inserted into theelectrode protection tubes 275 may be oxidized by the heat generatedfrom the heater 207. By filling an inert gas such as an N₂ gas or thelike into the electrode protection tubes 275, or by purging the interiorof the electrode protection tubes 275 with an inert gas such as an N₂gas or the like through the use of an inert gas purge mechanism, it ispossible to reduce the concentration of O within the electrodeprotection tubes 275 and to prevent oxidation of the rod-shapedelectrodes 269 and 270.

The exhaust pipe 231 configured to exhaust the internal atmosphere ofthe process chamber 201 is installed in the reaction tube 203. A vacuumpump 246 as a vacuum exhaust device is coupled to the exhaust pipe 231via a pressure sensor 245 as a pressure detector (pressure detectionpart) which detects the internal pressure of the process chamber 201 andan auto pressure controller (APC) valve 244 as a pressure regulator(pressure regulation part). The APC valve 244 is a valve configured sothat the vacuum exhaust of the interior of the process chamber 201 andthe stop of the vacuum exhaust can be performed by opening and closingthe APC valve 243 while operating the vacuum pump 246 and so that theinternal pressure of the process chamber 201 can be adjusted byadjusting an opening degree of the APC valve 243 based on the pressureinformation detected by the pressure sensor 245 while operating thevacuum pump 246. An exhaust system is mainly configured by the exhaustpipe 231, the APC valve 244 and the pressure sensor 245. The vacuum pump246 may be regarded as being included in the exhaust system.

A seal cap 219, which serves as a furnace opening cover configured tohermetically seal a lower end opening of the reaction tube 203, isinstalled under the reaction tube 203. The seal cap 219 is configured tomake contact with the lower end of the reaction tube 203 at a lower sidein the vertical direction. The seal cap 219 is made of metal such as,e.g., SUS or the like, and is formed in a disc shape. An O-ring 220,which is a seal member making contact with the lower end portion of thereaction tube 203, is installed on an upper surface of the seal cap 219.A rotation mechanism 267 configured to rotate the boat 217, which willbe described later, is installed at the opposite side of the seal cap219 from the process chamber 201. A rotary shaft 255 of the rotationmechanism 267, which penetrates through the seal cap 219, is connectedto the boat 217. The rotation mechanism 267 is configured to rotate thewafers 200 by rotating the boat 217. The seal cap 219 is configured tobe vertically moved up and down by a boat elevator 115 which is anelevator mechanism vertically installed outside the reaction tube 203.The boat elevator 215 is configured to load and unload the boat 217 intoand from the process chamber 201 by moving the seal cap 219 up and down.That is to say, the boat elevator 115 is configured as a transfer device(transfer mechanism) which transfers the boat 217, i.e., the wafers 200,into and out of the process chamber 201.

The boat 217 serving as a substrate support part is configured tosupport a plurality of, e.g., 25 to 200, wafers 200 in such a state thatthe wafers 200 are arranged in a horizontal posture and in multiplestages along a vertical direction with the centers of the wafers 200aligned with one another. That is to say, the boat 217 is configured toarrange the wafers 200 in a spaced-apart relationship. The boat 217 ismade of, for example, a heat resistant material such as quartz or SiC.Heat insulating plates 218 made of, for example, a heat resistantmaterial such as quartz or SiC are installed in a lower portion of theboat 217 in a horizontal posture and in multiple stages. With thisconfiguration, it is hard for heat generated from the heater 207 to beradiated to the seal cap 219. However, the present embodiment is notlimited to this configuration. For example, instead of installing theheat insulating plates 218 in the lower portion of the boat 217, a heatinsulating tube as a tubular member made of a heat resistant materialsuch as quartz or SiC may be installed under the boat 217.

A temperature sensor 263 serving as a temperature detector is installedin the reaction tube 203. Based on temperature information detected bythe temperature sensor 263, a state of supplying electric power to theheater 207 is adjusted such that the interior of the process chamber 201has a desired temperature distribution. Similar to the nozzles 249 a and249 b, the temperature sensor 263 is formed in an L-like shape. Thetemperature sensor 263 is installed along the inner wall of the reactiontube 203.

As illustrated in FIG. 3, a controller 121, which is a control part(control means), may be configured as a computer including a centralprocessing unit (CPU) 121 a, a random access memory (RAM) 121 b, amemory device 121 c, and an I/O port 121 d. The RAM 121 b, the memorydevice 121 c and the I/O port 121 d are configured to exchange data withthe CPU 121 a via an internal bus 121 e. An input/output device 122formed of, e.g., a touch panel or the like, is connected to thecontroller 121.

The memory device 121 c is configured by, for example, a flash memory, ahard disc drive (HDD), or the like. A control program for controllingoperations of a substrate-processing apparatus, a process recipe inwhich procedures and conditions of a substrate process as describedlater or the like is specified, or the like is readably stored in thememory device 121 c. The process recipe functions as a program forcausing the controller 121 to execute each sequence in the substrateprocess (to be described later) to obtain a predetermined result.Hereinafter, the process recipe and the control program will begenerally and simply referred to as a “program”. Furthermore, theprocess recipe will be simply referred to as a “recipe”. When the term“program” is used herein, it may indicate a case of including only therecipe, a case of including only the control program, or a case ofincluding both the recipe and the control program. The RAM 121 b isconfigured as a memory area (work area) in which a program or data readby the CPU 121 a is temporarily stored.

The I/O port 121 d is connected to the MFCs 241 a to 241 e, the valves243 a to 243 e, the pressure sensor 245, the APC valve 244, the vacuumpump 246, the heater 207, the temperature sensor 263, the rotationmechanism 267, the boat elevator 115, the matcher 272, thehigh-frequency power source 273, and the like.

The CPU 121 a is configured to read the control program from the memorydevice 121 c and execute the same. The CPU 121 a is also configured toread the process recipe from the memory device 121 c according to aninput of an operation command from the input/output device 122. Inaddition, the CPU 121 a is configured to control, according to thecontents of the recipe thus read, the flow rate adjusting operation ofvarious kinds of gases performed by the MFCs 241 a to 241 e, theopening/closing operation of the valves 243 a to 243 e, theopening/closing operation of the APC valve 244, the pressure regulatingoperation performed by the APC valve 244 based on the pressure sensor245, the driving and stopping of the vacuum pump 246, the temperatureadjusting operation performed by the heater 207 based on the temperaturesensor 263, the operation of rotating the boat 217 with the rotationmechanism 267 and adjusting the rotation speed of the boat 217, theoperation of moving the boat 217 up and down with the boat elevator 115,the impedance adjustment operation performed by the matcher 272, thepower supply operation performed by the high-frequency power source 273,and the like.

The controller 121 may be configured by installing, on the computer, theaforementioned program stored in an external memory device 123 (forexample, a magnetic tape, a magnetic disc such as a flexible disc or ahard disc, an optical disc such as a CD or DVD, a magneto-optical discsuch as an MO, a semiconductor memory such as a USB memory or a memorycard). The memory device 121 c or the external memory device 123 isconfigured as a computer-readable recording medium. Hereinafter, thememory device 121 c and the external memory device 123 will be generallyand simply referred to as a “recording medium.” When the term “recordingmedium” is used herein, it may indicate a case of including only thememory device 121 c, a case of including only the external memory device123, or a case of including both the memory device 121 c and theexternal memory device 123. Furthermore, the program may be provided tothe computer using a communication means such as the Internet or adedicated line, instead of using the external memory device 123.

(2) Film Forming Process

Using the aforementioned substrate-processing apparatus, a sequenceexample of forming a C-containing nitride film as a protective film on asubstrate on which an oxide film is formed, which is one of theprocesses for manufacturing a semiconductor device, will be describedwith reference to FIG. 4. In the following descriptions, the operationsof the respective parts constituting the substrate-processing apparatusare controlled by the controller 121.

In the film forming sequence illustrated in FIG. 4, there are performed:a step of providing a wafer 200 as a substrate on which a silicon oxidefilm (SiO film) as an oxide film is formed (in a substrate providingstep), a step of pre-processing a surface of the SiO film (in apre-processing step), and a step of forming a silicon nitride film (SiNfilm) containing C as a protective film on the surface of the SiO filmwhich has been pre-processed, by implementing, a predetermined number oftimes (n times), a cycle which non-simultaneously (alternately) performsstep 1 of supplying a DCS gas as a precursor gas to the wafer 200, step2 of supplying a C₃H₆ gas as a C-containing gas to the wafer 200, andstep 3 of supplying an NH₃ gas as an N-containing gas to the wafer 200(in a protective film forming step). The SiN film containing C isreferred to as a C-added (doped) SiN film or a C-containing SiN film.

Furthermore, in the pre-processing step illustrated in FIG. 4, there isperformed: a cycle which non-simultaneously performs step 1 p ofsupplying a DCS gas to the wafer 200, step 2 p of supplying a C₃H₆ gasto the wafer 200, and step 3 p of supplying an NH₃ gas to the wafer 200,a predetermined number of times (m times). At this time, a siliconnitride layer (SiN layer) containing O and C as a seed layer is formedon the surface of the SiO film using the SiO film as an oxygen source (Osource). The SiN layer containing O and C is referred to as a C-addedsilicon oxynitride layer (SiON layer) or a C-containing SiON layer.

In the above, m is an integer of 1 or more. Further, n is an integergreater than m, i.e., an integer of 2 or more. In the presentdisclosure, for the sake of convenience, the sequence of the filmforming process illustrated in FIG. 4 may sometimes be denoted asfollows. The same denotation will be used in the modifications and otherembodiments, which will be described later.

(DCS→C₃H₆→NH₃)×m→(DCS→C₃H₆→NH₃)×n⇒C-containing SiN film/SiN layercontaining O and C

When the term “wafer” is used herein, it may refer to “a wafer itself”or “a laminated body (aggregate) of a wafer and a predetermined layer orfilm formed on the surface of the wafer”. That is to say, a waferincluding a predetermined layer or film formed on its surface may bereferred to as a wafer. In addition, when the phrase “a surface of awafer” is used herein, it may refer to “a surface (exposed surface) of awafer itself” or “a surface of a predetermined layer or film formed on awafer, namely an uppermost surface of the wafer as a laminated body”.

Accordingly, in the present disclosure, the expression “a predeterminedgas is supplied to a wafer” may mean that “a predetermined gas isdirectly supplied to a surface (exposed surface) of a wafer itself” orthat “a predetermined gas is supplied to a layer or film formed on awafer, namely to an uppermost surface of a wafer as a laminated body.”Furthermore, in the present disclosure, the expression “a predeterminedlayer (or film) is formed on a wafer” may mean that “a predeterminedlayer (or film) is directly formed on a surface (exposed surface) of awafer itself” or that “a predetermined layer (or film) is formed on alayer or film formed on a wafer, namely on an uppermost surface of awafer as a laminated body.”

In addition, when the term “substrate” is used herein, it may besynonymous with the term “wafer.”

(Substrate Provision Step)

When a plurality of wafers 200 are charged in the boat 217 (wafercharging), as illustrated in FIG. 1, the boat 217 supporting theplurality of wafers 200 is lifted up by the boat elevator 115 and isloaded into the process chamber 201 (boat loading). In this state, theseal cap 219 seals the lower end of the reaction tube 203 through theO-ring 220 b.

As described above, the SiO film as an oxide film is formed in advanceon at least a portion of the surface of the wafer 200. This filmfunctions as a supply source of O added to a seed layer, i.e., an Osource, at a pre-processing step which will be described later. Further,this film becomes at least a portion of a base film when forming aprotective film at the pre-processing step to be described later. Also,this film may be a film to be protected by the protective film in anetching process which will be described later. The SiO film may beformed so as to cover the entire surface of the wafer 200 or so as tocover only a portion of the entire surface of the wafer 200. In additionto the SiO film, for example, an Si-containing film such as a siliconoxynitride film (SiON film), a silicon oxycarbide film (SiOC film), or asilicon oxycarbonitride film (SiOCN film), or a metal oxide film, i.e.,a high dielectric constant insulating film (high-k film), such as analuminum oxide film (AlO film), a hafnium oxide film (HfO film), azirconium oxide film (ZrO film), or a titanium oxide film (TiO film) maybe formed as the oxide film. The oxide film (or the oxynitride film, theoxycarbide film, or the oxycarbonitride film) referred to hereinincludes not only an oxide film intentionally formed by performing aspecified process such as, e.g., a CVD process, a plasma CVD process, athermal oxidation process, or a plasma oxidation process, but also anatural oxide film naturally formed as the surface of the wafer 200 isexposed to the air during the transfer of the wafer 200.

(Pressure Regulation and Temperature Adjustment Step)

The interior of the process chamber 201, namely the space in which thewafers 200 are located, is vacuum-exhausted (depressurization-exhausted)by the vacuum pump 246 so as to reach a desired pressure (degree ofvacuum). In this operation, the internal pressure of the process chamber201 is measured by the pressure sensor 245. The APC valve 244 isfeedback-controlled based on the measured pressure information. Thevacuum pump 246 may be continuously activated at least until theprocessing of the wafers 200 is completed. The wafers 200 in the processchamber 201 are heated by the heater 207 to a desired film formationtemperature. In this operation, the state of supplying electric power tothe heater 207 is feedback-controlled based on the temperatureinformation detected by the temperature sensor 263 such that theinterior of the process chamber 201 has a desired temperaturedistribution. In addition, the heating of the interior of the processchamber 201 by the heater 207 may be continuously performed at leastuntil the processing of the wafers 200 is completed. The rotation of theboat 217 and the wafers 200 by the rotation mechanism 267 begins. Therotation of the boat 217 and the wafers 200 by the rotation mechanism267 may be continuously performed at least until the processing of thewafers 200 is completed.

(Pre-Processing Step)

Thereafter, the following three steps, i.e., steps 1 p to 3 p, areperformed.

[Step 1 p]

At this step, a DCS gas is supplied to the wafers 200 in the processchamber 201.

Specifically, the valve 243 a is opened to allow the DCS gas to flowthrough the gas supply pipe 232 a. The flow rate of the DCS gas isadjusted by the MFC 241 a. The DCS gas is supplied into the processchamber 201 via the nozzle 249 a and is exhausted from the exhaust pipe231. At this time, the DCS gas is supplied to the wafer 200.Simultaneously, the valve 243 d is opened to allow an N₂ gas to flowthrough the gas supply pipe 232 d. The flow rate of the N₂ gas isadjusted by the MFC 241 d. The N₂ gas is supplied into the processchamber 201 together with the DCS gas and is exhausted from the exhaustpipe 231.

Furthermore, in order to prevent the DCS gas from entering the nozzle249 b and the buffer chamber 237, the valve 243 e is opened to allow theN₂ gas to flow through the gas supply pipe 232 e. The N₂ gas is suppliedinto the process chamber 201 via the gas supply pipe 232 b, the nozzle249 b and the buffer chamber 237 and is exhausted from the exhaust pipe231.

At this time, by appropriately adjusting the APC valve 244, the internalpressure of the process chamber 201 may be set at a pressure which fallswithin a range of, for example, 1 to 2,666 Pa, specifically 67 to 1,333Pa. The supply flow rate of the DCS gas controlled by the MFC 241 a maybe set at a flow rate which falls within a range of, for example, 10 to2,000 sccm, specifically 10 to 1,000 sccm. The supply flow rates of theN₂ gas controlled by the MFCs 241 d and 241 e may be respectively set ata flow rate which falls within a range of, for example, 100 to 10,000sccm. The time period during which the DCS gas is supplied to the wafer200, namely a gas supply time period (irradiation time period), may beset at a time period which falls within a range of, for example, 1 to120 seconds, specifically 1 to 60 seconds. The temperature of the heater207 is set such that the temperature of the wafer 200 becomes atemperature which falls within a range of, for example, 250 to 700degrees C., specifically 300 to 650 degrees C., more specifically 350 to600 degrees C.

If the temperature of the wafer 200 is lower than 250 degrees C., apractical deposition rate may not be obtained because the DCS is hardlychemisorbed onto the wafer 200. This may be solved by setting thetemperature of the wafer 200 to become 250 degrees C. or more. Bysetting the temperature of the wafer 200 to become 300 degrees C. ormore, further, 350 degrees C. or more, it is possible to furthersufficiently adsorb the DCS onto the wafer 200, thus obtaining a furthersufficient deposition rate.

If the temperature of the wafer 200 exceeds 700 degrees C., an excessiveCVD reaction (excessive vapor phase reaction) occurs to degrade the filmthickness uniformity. This makes it difficult to control the filmthickness uniformity. By setting the temperature of the wafer to become700 degrees C. or less, i.e., by causing an appropriate vapor phasereaction to occur, it becomes possible to suppress such degradation ofthe film thickness uniformity, and to control the film thicknessuniformity. In particular, by setting the temperature of the wafer 200to become 650 degrees C. or less, further, 600 degrees C. or less, thesurface reaction becomes dominant relative to the vapor phase reaction.This makes it easy to assure the film thickness uniformity, facilitatingthe control of the film thickness uniformity.

Accordingly, it is desirable that the temperature of the wafer 200 isset at a temperature which falls within a range of 250 to 700 degreesC., specifically 300 to 650 degrees C., more specifically 350 to 600degrees C.

By supplying the DCS gas to the wafer 200 under the aforementionedconditions, a first layer, for example, an Si-containing layercontaining Cl having a thickness of approximately less than one atomiclayer to several atomic layers is formed on the wafer 200 (a base filmon which the SiO film is formed). The Si-containing layer containing Clmay include an Si layer containing Cl, an adsorption layer of DCS, orboth. Further, O contained in the underlying SiO film may be introducedinto the first layer. That is to say, an Si-containing layer containingO and Cl may be formed as the first layer. In the present disclosure,the first layer containing O (the Si-containing layer containing O andCl) may be simply referred to as an Si-containing layer containing Clfor the sake of convenience.

The Si layer containing Cl is a general name which encompasses not onlya continuous layer or discontinuous layer formed of Si and containing Clbut also an Si thin film containing Cl obtained by superposing suchlayers. The continuous layer formed of Si and containing Cl may bereferred to as an Si thin film containing Cl. Si constituting the Silayer containing Cl includes not only Si whose bond to Cl is notcompletely broken but also Si whose bond to Cl is completely broken.

The adsorption layer of the DCS includes not only a continuousadsorption layer formed of DCS molecules but also a discontinuousadsorption layer formed of DCS molecules. That is to say, the adsorptionlayer of the DCS includes an adsorption layer having a thickness of onemolecular layer formed of DCS molecules or an adsorption layer having athickness of less than one molecular layer. The DCS moleculesconstituting the adsorption layer of the DCS include molecules in whicha bond of Si and Cl or a bond of Si and H is partially broken. That isto say, the adsorption layer of the DCS may include a physicaladsorption layer of the DCS, a chemical adsorption layer of the DCS, orboth.

Here, the layer having a thickness of less than one atomic layer refersto an atomic layer formed discontinuously. The layer having a thicknessof one atomic layer refers to an atomic layer formed continuously. Thelayer having a thickness of less than one molecular layer refers to amolecular layer formed discontinuously. The layer having a thickness ofone molecular layer refers to a molecular layer formed continuously. TheSi-containing layer containing Cl may include both an Si layercontaining Cl and an adsorption layer of the DCS. As described above,the expressions such as “one atomic layer”, “several atomic layers”, andthe like will be used for the Si-containing layer containing Cl.

Under a condition in which the DCS gas is autolyzed (or pyrolyzed),namely a condition in which a pyrolysis reaction of the DCS gas occurs,Si is deposited on the wafer 200 to form the Si layer containing Cl.Under a condition in which the DCS gas is not autolyzed (or pyrolyzed),namely a condition in which a pyrolysis reaction of the DCS gas does notoccur, the DCS is adsorbed onto the wafer 200 to form the adsorptionlayer of the DCS. From the viewpoint of increasing a deposition rate,when the Si layer containing Cl is formed on the wafer 200, thedeposition rate may be greater than that when the adsorption layer ofthe DCS gas is formed on the wafer 200.

If the thickness of the first layer formed on the wafer 200 exceedsseveral atomic layers, a modifying action at step 3 p as described laterfails to reach the entirety of the first layer. A minimum value of thethickness of the first layer which can be formed on the wafer 200 isless than one atomic layer. Accordingly, it is desirable that thethickness of the first layer falls within a range of approximately lessthan one atomic layer to several atomic layers. By setting the thicknessof the first layer to become equal to one atomic layer or less, namelyone atomic layer or less than one atomic layer, it is possible torelatively increase the modifying action at step 3 p, which will bedescribed later, and to shorten the time required in modifying the firstlayer at step 3 p. It is also possible to shorten the time required informing the first layer at step 1 p. Eventually, a Process time per onecycle can be reduced and a total Process time can also be reduced. Thatis to say, the deposition rate can be increased. Further, by setting thethickness of the first layer to become equal to one atomic layer orless, it is possible to enhance the controllability of the filmthickness uniformity.

After the first layer is formed, the valve 243 a is closed to stop thesupply of the DCS gas. At this time, the interior of the process chamber201 is vacuum-exhausted by the vacuum pump 246 while keeping the APCvalve 244 opened. Thus, the unreacted DCS gas or the DCS gas contributedto the formation of the first layer, which remains within the processchamber 201, is removed from the interior of the process chamber 201. Atthis time, the supply of the N₂ gas into the process chamber 201 ismaintained while keeping the valves 243 d and 243 e opened. The N₂ gasacts as a purge gas. This makes it possible to enhance the effect ofremoving the gas, which remains within the process chamber 201, from theinterior of the process chamber 201.

At this time, the gas remaining within the process chamber 201 may notbe completely removed and the interior of the process chamber 201 maynot be completely purged. If the amount of the gas remaining within theprocess chamber 201 is small, there is no possibility that an adverseeffect is generated at step 2 p which will be performed later. In thiscase, the flow rate of the N₂ gas supplied into the process chamber 201does not need a large flow rate. For example, by supplying the N₂ gassubstantially in the same amount as the volume of the reaction tube 203(the process chamber 201), it is possible to perform a purge operationsuch that an adverse effect is not generated at step 2 p. By notcompletely purging the interior of the process chamber 201 in this way,it is possible to shorten the purge time and to improve the throughput.In addition, it is also possible to suppress the consumption of the N₂gas to a necessary minimum level.

As the precursor gas, for example, it may be possible to use, inaddition to the DCS gas, an inorganic precursor gas such as amonochlorosilane (SiH₃Cl, abbreviation: MCS) gas, a trichlorosilane(SiHCl₃, abbreviation: TCS) gas, a tetrachlorosilane gas, i.e., silicontetrachloride (SiCl₄, abbreviation: STC) gas, a hexachlorodisilane(Si₂Cl₆, abbreviation: HCDS) gas, an octachlorotrisilane (Si₃Cl₈,abbreviation: OCTS) gas, a monosilane (SiH₄, abbreviation: MS) gas, adisilane (Si₂H₆, abbreviation: DS) gas, a trisilane (Si₃H₈,abbreviation: TS) gas or the like. In addition, as the precursor gas, itmay be possible to use, for example, an organic precursor gas such as atetrakis-dimethylaminosilane (Si[N(CH₃)₂]₄, abbreviation: 4DMAS) gas, atris-dimethylaminosilane (Si[N(CH₃)₂]₃H, abbreviation: 3DMAS) gas, abis-diethylaminosilane (Si[N(C₂H₅)₂]₂H₂, abbreviation: BDEAS) gas, abis(tertiarybutylamino)silane (SiH₂[NH(C₄H₉)]₂, abbreviation: BTBAS) gasor the like. In the case of using a precursor gas containing Cl, it isdesirable to use a precursor having less Cl in number in compositionformula (in one molecule). For example, it is desirable to use a DCS gasor an MCS gas.

As the inert gas, for example, it may be possible to use, in addition tothe N₂ gas, a rare gas such as an Ar gas, a He gas, a Ne gas, a Xe gasor the like.

[Step 2 p]

After step 1 p is completed, the C₃H₆ gas is supplied to the wafer 200in the process chamber 201.

At this step, the opening/closing control of the valves 243 c, 243 d,and 243 e is performed in the same procedure as the opening/closingcontrol of the valves 243 a, 243 d, and 243 e performed at step 1 p. TheC₃H₆ gas is supplied from the gas supply pipe 232 c into the processchamber 201 through the gas supply pipe 232 b, the nozzle 249 b, and thebuffer chamber 237. The supply flow rate of the C₃H₆ gas controlled bythe MFC 241 c is set at a flow rate which falls within a range of, forexample, 100 to 10,000 sccm. The internal pressure of the processchamber 201 is set at a pressure which falls within a range of, forexample, 1 to 5,000 Pa, specifically, 1 to 4,000 Pa. A partial pressureof the C₃H₆ gas within the process chamber 201 is set at a pressurewhich falls within a range of, for example, 0.01 to 4,950 Pa. The timeperiod during which the C₃H₆ gas is supplied to the wafer 200, namely agas supply time period (irradiation time period), may be set at a timeperiod which falls within a range of, for example, 1 to 200 seconds,specifically 1 to 120 seconds, more specifically 1 to 60 seconds. Otherprocess conditions may be similar to, for example, the processconditions of step 1 p.

By supplying the C₃H₆ gas to the wafer 200 under the aforementionedconditions, a C-containing layer having a thickness of less than oneatomic layer, namely a discontinuous C-containing layer, is formed onthe surface of the first layer (the Si-containing layer containing O andCl) formed on the wafer 200. The C-containing layer may be a C layer ora chemical adsorption layer of C₃H₆, or may include both. Further, inorder to reliably perform the reaction between the first layer on whichthe C-containing layer is formed and the NH₃ gas, namely the formationof a silicon nitride layer containing O and C (SiN layer containing Oand C), at step 3 p which will be described later, it is desirable tostop the supply of the C₃H₆ gas before the adsorption reaction of C₃H₆to the surface of the first layer is saturated, namely before theC-containing layer such as the adsorption layer (chemical adsorptionlayer) of C₃H₆ formed on the surface of the first layer or the likebecomes a continuous layer (while the C-containing layer is adiscontinuous layer).

After the C-containing layer is formed on the surface of the firstlayer, the valve 243 c is closed to stop the supply of the C₃H₆ gas.Then, an unreacted C₃H₆ gas, the C₃H₆ gas contributed to the formationof the C-containing layer, or the reaction byproduct, which remainswithin the process chamber 201, is removed from the interior of theprocess chamber 201 by the same process procedures as used at step 1 p.At this time, similar to step 1 p, the gas or the like remaining withinthe process chamber 201 may not be completely removed.

As the C-containing gas, it may be possible to use, in addition to theC₃H₆ gas, a hydrocarbon—based gas such as, for example, an acetylene(C₂H₂) gas, an ethylene (C₃H₄) gas or the like. As the inert gas, forexample, it may be possible to use, in addition to the N₂ gas, a raregas such as an Ar gas, a He gas, a Ne gas, a Xe gas or the like.

[Step 3 p]

After step 2 p is completed, the NH₃ gas is supplied to the wafer 200 inthe process chamber 201.

At this step, the opening/closing control of the valves 243 b, 243 d,and 243 e is performed in the same procedure as the opening/closingcontrol of the valves 243 a, 243 d, and 243 e performed at step 1 p. TheNH₃ gas is supplied from the gas supply pipe 232 b into the processchamber 201 through the nozzle 249 b and the buffer chamber 237. Thesupply flow rate of the NH₃ gas controlled by the WC 241 b is be set ata flow rate which falls within a range of, for example, 100 to 10,000sccm. The internal pressure of the process chamber 201 is set at apressure which falls within a range of, for example, 1 to 4,000 Pa,specifically, 1 to 3,000 Pa. The partial pressure of the NH₃ gas withinthe process chamber 201 is set at a pressure which falls within a rangeof, for example, 0.01 to 3,960 Pa. By setting the internal pressure ofthe process chamber 201 at such a relatively high pressure, it becomespossible to thermally activate the NH₃ gas under a non-plasma condition.If the NH₃ gas is thermally activated and supplied, a relatively moresoft reaction can occur, thus relatively softly performing a nitridingprocess which will be described later. The time period during which thethermally activated NH₃ gas is supplied to the wafer 200, namely a gassupply time period (irradiation time period), may be set at a timeperiod which falls within a range of, for example, 1 to 120 seconds,specifically, 1 to 60 seconds. Other process conditions may be similarto, for example, the process conditions applied at step 1 p.

By supplying the NH₃ gas to the wafer 200 under the aforementionedconditions, at least a portion of the first layer on which theC-containing layer is formed is nitrided (modified). As the first layeron which the C-containing layer is formed is modified, a second layercontaining Si, O, C, and N, namely an SiN layer (C-containing SiONlayer) containing O and C, is formed. When forming the second layer, animpurity such as Cl or the like contained in the first layer on whichthe C-containing layer is formed constitutes a gaseous materialcontaining at least Cl during the process of the modification reactionby the NH₃ gas and is discharged from the interior of the processchamber 201. That is to say, an impurity such as Cl or the like of thefirst layer on which the C-containing layer is formed is drawn out oreliminated from the first layer on which the C-containing layer isformed so as to be separated therefrom. Accordingly, the second layerbecomes a layer with less impurity such as Cl or the like than that ofthe first layer on which the C-containing layer is formed.

After the second layer is formed, the valve 243 b is closed to stop thesupply of the NH₃ gas. Then, an unreacted NH₃ gas, the NH₃ gascontributed to the formation of the second layer, or the reactionbyproduct, which remains within the process chamber 201, are excludedfrom the interior of the process chamber 201 under the same processprocedures as those used at step 1 p. At this time, similar to step 1 p,the gas or the like remaining within the process chamber 201 may not becompletely excluded.

As the N-containing gas, for example, it may be possible to use, inaddition to the NH₃ gas, a hydrogen nitride—based gas such as an N₂H₂gas, an N₂H₄ gas, or an N₃H₈ gas, a gas containing such compound or thelike. As the inert gas, for example, it may be possible to use, inaddition to the N₂ gas, a rare gas such as an Ar gas, a He gas, a Negas, a Xe gas or the like.

(Performing a Predetermined Number of Times)

A cycle which non-simultaneously, i.e., non-synchronously, performssteps 1 p to 3 p described above is implemented once or more (m times).Thus, an SiN layer containing O and C having a predetermined compositionand a predetermined film thickness can be formed as a seed layer on thewafer 200 (on the SiO film). The seed layer functions as a block layer(diffusion barrier layer) to suppress the spreading of O to theprotective film from the underlying SiO film at a protective filmforming step which will be described later.

It is desirable that the thickness of the seed layer (the SiN layercontaining O and C) is set at a thickness which falls within a range of,for example, 0.05 to 0.3 nm (0.5 to 3 Å), specifically, 0.1 to 0.2 nm (1to 2 Å).

If the thickness of the seed layer is less than 0.5 Å, the function ofthe seed layer as the aforementioned block layer may be insufficient tospread the O contained in the underlying SiO film to the protectivefilm. By setting the thickness of the seed layer to become 0.5 Å ormore, it becomes possible to sufficiently obtain the function of theseed layer as the block layer and to avoid the spreading (addition) of Oto the protective film. By setting the thickness of the seed layer tobecome 1 Å or more, it becomes possible to enhance the function of theseed layer as the block layer and to reliably avoid the spreading of Oto the protective film.

If the thickness of the seed layer exceeds 3 Å, the time period requiredin forming the seed layer may be lengthened to degrade the productivityof the substrate process. By setting the thickness of the seed layer tobecome 3 Å or less, it becomes possible to shorten the time periodrequired in forming the seed layer, increasing the productivity of thesubstrate process. By setting the thickness of the seed layer to become2 Å or less, it becomes possible to further shorten the time periodrequired in forming the seed layer, further increasing the productivityof the substrate process.

Thus, the thickness of the seed layer may be set at a thickness whichfalls within a range of, for example, 0.5 to 3 Å, specifically, 1 to 2Å. By setting the number of performing the cycle at the pre-processingstep to fall within a range of, for example, 5 to 30 times,specifically, 10 to 20 times, it is possible to set the thickness of theseed layer to fall within the aforementioned range. Further, it isdesirable that the thickness of the seed layer is set to fall within theaforementioned range and to become thinner than that of the C-containingSiN film formed at the protective film forming step. For example, if thethickness of the C-containing SiN film is set at a thickness of 3 Å, itis desirable that the thickness of the seed layer is set to fall withina range of approximately 0.5 to 1 Å.

(Protective Film Forming Step)

After the formation of the seed layer is completed, steps 1 to 3 areperformed as described above. The process procedures and processconditions of steps 1 to 3 may be similar to, for example, those ofsteps 1 p to 3 p. At the protective film forming step, spreading of Ofrom the SiO film is suppressed by the seed layer mentioned above. Thus,by performing steps 1 to 3, an SiN layer not containing O and containingC (C-containing SiN layer not containing O) is formed on the seed layer.

Further, a cycle which non-simultaneously, i.e., non-synchronously,performs steps 1 to 3 described above is implemented two or more times(n times). Thus, an SiN film not containing O and containing C (theC-containing SiN film) having a predetermined composition and apredetermined film thickness can be formed on the wafer 200 (on the SiNlayer containing O and C). The number of times (n times) of implementingthe cycle at this step may be set greater than the number of times (mtimes) of implementing the cycle at the pre-processing step mentionedabove (n>m). The C-containing SiN film functions as a protective film toprotect an underlying SiO film at an etching process which will bedescribed later. FIG. 9 illustrates a cross sectional structure of afilm formed on the wafer 200 according to the film forming sequenceillustrated in FIG. 4.

It is desirable that the thickness of the protective film (theC-containing SiN film) is set at a thickness which falls within a rangeof 0.2 to 10 nm (2 to 100 Å), specifically 0.5 to 10 nm (5 to 100 Å),more specifically 1 to 10 nm (10 to 100 Å).

If the film thickness of the C-containing SiN film is less than 2 Å,this film may not function as the protective film. By setting the filmthickness of the C-containing SiN film to become 2 Å or more, this filmcan function as the protective film. By setting the film thickness ofthe C-containing SiN film to become 5 Å or more, this film cansufficiently function as the protective film. Further, by setting thefilm thickness of the C-containing SiN film to become 10 Å or more, itbecomes possible to further enhance the function of the C-containing SiNfilm as the protective film, and it becomes possible to allow this filmto reliably function as the protective film.

Furthermore, if the film thickness of the C-containing SiN film exceeds100 Å, the technical meaning of adding C to the SiN film may be reduced.That is to say, if the film thickness exceeds 100 Å, even when C is notadded to the SiN film, namely even when the protective film is formed ofan SiN film not containing C, this film can sufficiently function as theprotective film. This is because, if the film thickness of the SiN filmexceeds 100 Å, the influence of a pin hole of the film becomessufficiently small.

Here, the term “pin hole” refers to a path along which an etchant suchas an etching gas or an etching solution enters toward a base side ofthe film, namely the SiO film side in the present embodiment, when theetchant is supplied to the film. The pin hole is not limited to a caseof being formed as a physical hole. For example, the pin hole may beformed due to various factors such as a local crack, a degradation of alocal film density, an increase in a local defect density, or a changein a local composition or a crystal structure, which may occur in afilm. With the pin hole present in the protective film, when an etchantis supplied to the protective film, the etchant may reach the base sidethrough the pin hole so that the base side may be etch-damaged. Further,the etchant may enter into the pin hole to cause the protective filmitself to be etched, resulting in a degradation of the function as theprotective film.

According to extensive research of the present inventors, it wasconfirmed that, if the film thickness of the SiN film not containing Cis small, a pin hole is easy to generate. The present inventorsconfirmed that, when the protective film is formed of the SiN film notcontaining C, if the film thickness thereof is 100 Å or less, influenceof the pin hole may occur, and if the film thickness is 30 Å or less,the influence of the pin hole is increased to make the function of theSiN film as the protective film insufficient. In contrast, by adding Cto the SiN film, namely by forming the protective film of theC-containing SiN film, even when the film thickness is 100 Å or less, itbecomes possible to suppress the generation of the pin hole and toenhance the function as the protective film. It is considered that thisis because an Si—C bond has a stronger bonding force than an Si—N bondand it is possible to reduce a defect in a film by including an Si—Cbond by adding C to the film. The present inventors confirmed that, ifthe protective film is formed of the C-containing SiN film, even whenthe film thickness of the SiN film is 100 Å or less, ultimately 30 Å orless, the SiN film can sufficiently function as the protective film. Inthis regard, it may be considered that forming the protective film ofthe C-containing SiN film is meaningful particularly if the protectivefilm is required to have a thin film having a film thickness of 100 Å orless.

From the above, it is desirable that the film thickness of theC-containing SiN film is set at a thickness which falls within a rangeof 2 to 100 Å, specifically 5 to 100 Å, more specifically 10 to 100 Å.As described above, it is desirable that the film thickness of theC-containing SiN film is set larger than the thickness of the seedlayer. Further, it was confirmed that, even when the film thickness ofthe C-containing SiN film is set at a thickness which falls within arange of 2 to 30 Å, specifically 5 to 30 Å, more specifically 10 to 30Å, it is possible to suppress the generation of the pin hole and toallow the SiN film to sufficiently function as the protective film.

Furthermore, it is desirable that a concentration of C in the protectivefilm (the C-containing SiN film) is set at a concentration which fallswithin a range of, for example, 3 to 10 atomic %, specifically 5 to 9atomic %, more specifically 7 to 8 atomic %.

If the concentration of C in the C-containing SiN film is less than 3atomic %, etching tolerance of the film may be insufficient and a pinhole may be easily generated. Thus, the C-containing SiN film may notfunction as the protective film. By setting the concentration of C inthe C-containing SiN film to become 3 atomic % or more, it is possibleto increase the etching tolerance of the film, to suppress thegeneration of the pin hole, and to allow the film to function as theprotective film. By setting the concentration of C in the C-containingSiN film to become 5 atomic % or more, it is possible to increase Si—Cbonds included in the film and allow the film to sufficiently functionas the protective film. By setting the concentration of C in theC-containing SiN film to become 7 atomic % or more, it is possible tofurther increase Si—C bonds included in the film and allow the film toreliably function as the protective film.

If the concentration of C in the C-containing SiN film exceeds 10 atomic%, C included in the film may spread to other films, for example,degrading a function of the semiconductor device or causing a defectiveprocess of the film. By setting the concentration of C in theC-containing SiN film to become 10 atomic % or less, it is possible tosuppress the spreading of C contained in the film. By setting theconcentration of C in the C-containing SiN film to become 9 atomic % orless, it is possible to sufficiently suppress the spreading of Ccontained in the film. By setting the concentration of C in theC-containing SiN film to become 8 atomic % or less, it is possible toreliably suppress the spreading of C contained in the film.

As described above, it is desirable that the concentration of C in theC-containing SiN film is set at a concentration which falls within arange of 3 to 10 atomic %, specifically, 5 to 9 atomic %, morespecifically, 7 to 8 atomic %. It was confirmed that, by setting theprocess conditions of the protective film forming step to fall withinthe aforementioned process condition range, it is possible to set theconcentration of C in the C-containing SiN film at a concentrationwithin the aforementioned range.

Moreover, it is desirable that the aforementioned cycle is repeated aplural number of times. That is to say, it is desirable that thethickness of the C-containing SiN layer formed per cycle is set smallerthan a desired film thickness and the aforementioned cycle is repeated aplural number of times until the thickness of the C-containing SiN layerbecomes equal to the desired film thickness.

(Purge Step and Atmospheric Pressure Return Step)

After the formation of the protective film is completed, the N₂ gas issupplied from the respective gas supply pipes 232 d and 232 e into theprocess chamber 201 and is exhausted from the exhaust pipe 231. The N₂gas acts as a purge gas. Thus, the interior of the process chamber 201is purged and the gas or the reaction byproduct, which remains withinthe process chamber 201, is removed from the interior of the processchamber 201 (in a purging operation). Thereafter, the internalatmosphere of the process chamber 201 is substituted with an inert gas(in an inert gas substitution process). The internal pressure of theprocess chamber 201 is returned to an atmospheric pressure (in anatmospheric pressure return operation).

(Unloading Step)

Thereafter, the seal cap 219 is moved down by the boat elevator 115 toopen the lower end of the manifold 209. Then, the processed wafers 200supported on the boat 217 are unloaded from the lower end of thereaction tube 203 outside the reaction tube 203 (in a boat unloadingoperation). The processed wafers 200 are discharged from the boat 217(in a wafer discharging operation).

(3) Etching Process

After the wafers 200 are unloaded from the interior of the processchamber 201, additional film forming processes, a resist pattern formingprocess and the like are further performed on the wafers 200 which havebeen subjected to the film forming process. Then, the wafers 200 whichwere subjected to such processes are performed, and are carried into areaction chamber (second process chamber) included in an etching deviceserving as a second substrate processing part. Then, in a state wherethe interior of the reaction chamber is controlled to have apredetermined process pressure and a process temperature, an etching gasis supplied as an etchant to the wafers 200 in the reaction chamber toperform an etching process to the film or the like formed on thesurfaces of the wafers 200. At this time, the C-containing SiN filmformed on the wafers 200 functions as the protective film to protect theunderlying SiO film.

As the etching gas, it may be possible to use, for example, a hydrogenfluoride (HF) gas diluted with the N₂ gas, or the like. An example ofprocess conditions of the etching process is as follows:

Flow rate of the HF gas: 100 to 2,000 sccm, specifically 1,000 to 2,000sccm

Flow rate of the N₂ gas: 1,000 to 8,000 sccm, specifically 7,000 to8,000 sccm

Internal pressure of the reaction chamber: 133 to 26,600 Pa,specifically 13,300 to 26,600 Pa

Internal temperature of the reaction chamber: 50 to 100 degrees C.,specifically 50 to 75 degrees C.

Process time: 0.5 to 10 min., specifically 0.5 to 1 min.

After a predetermined period of time since the HF gas started to besupplied, when the etching process on the wafers 200 is completed, thesupply of the HF gas into the reaction chamber is stopped and theinterior of the reaction chamber is exhausted. Thereafter, after theinternal atmosphere of the reaction chamber is substituted with an inertgas and the internal pressure of the reaction chamber is returned toatmospheric pressure, the wafers 200 which have been subjected to theetching process are unloaded from the interior of the reaction chamber.

As the etchant, for example, it may be possible to use, in addition tothe HF gas, a fluoride-based gas such as a fluoride (F₂) gas or thelike, or a chloride-based gas such as a hydrogen chloride (HCl) gas orthe like. Process conditions of these cases may be similar to theprocess conditions described above. However, it is desirable that theinternal temperature of the reaction chamber is set at a temperaturewhich falls within a range of about 100 to 500 degrees C. Further, thesegases may be mixed to be used, an H-containing gas (reducing gas) suchas an H₂ gas or the like may be added to these gases so as to be used,or these gases may be activated by plasma so as to be used. As theetchant, it may also be possible to use an etching solution such as, forexample, an HF aqueous solution, an HCl aqueous solution or the like,rather than a gas.

(4) Effects According to the Present Embodiment

According to the present embodiment, one or more effects set forth belowmay be achieved.

(a) By forming the seed layer as a base film of the protective film inadvance, and allowing the seed layer to act as a block layer to suppressthe spreading of O from the SiO film, it becomes possible to suppressthe addition of O to the C-containing SiN film formed on the seed layer.This makes it possible to enhance film characteristics of theC-containing SiN film formed on the seed layer.

(b) By forming the seed layer on the wafer 200 in advance, it becomespossible to shorten the incubation time of the C-containing SiN filmformed on the seed layer. Further, by forming the seed layer as acontinuous layer, it becomes possible to allow the growth startingtimings of the C-containing SiN film to be uniform over the entirein-plane region of the wafers 200. This makes it possible to improve thestep coatability or film thickness uniformity of the C-containing SiNfilm, and to enhance the function thereof as the protective film.

(c) By forming the protective film of the C-containing SiN film, evenwhen the protective film is thinned, it becomes possible to form theprotective film as a film without a pin hole, i.e., a pin hole-freefilm. Accordingly, even when the protective film is thinned, it becomespossible to avoid an etching damage to the base film entailed by theetching process. In addition, by forming the protective film of the pinhole-free film, it becomes possible to suppress the etching of theprotective film itself entailed by the etching process and to avoid adegradation of the function of the C-containing SiN film as theprotective film.

(d) By forming the protective film of the C-containing SiN film, namelyby including an Si—C bond having a stronger bonding force than that ofan Si—N bond in a film, it is possible to form this film as a filmhaving higher tolerance (etching tolerance) to an etchant such as HF orthe like. This makes it possible to enhance the function of theC-containing SiN film as the protective film. Further, it becomespossible to suppress the etching of the protective film itself entailedby the etching process and to maintain the function of the C-containingSiN film as the protective film.

(e) In the film forming process, by non-simultaneously performing thesupply of the DCS gas to the wafer 200, the supply of the C₃H₆ gas tothe wafer 200, and the supply of the NH₃ gas to the wafer 200, itbecomes possible to enhance the step coatability or film thicknesscontrollability of the C-containing SiN film, compared with the casewhere the supplies of these gases are simultaneously performed. As aresult, it becomes possible to enhance the function of the C-containingSiN film as the protective film.

(f) The effects mentioned above can be similarly achieved in the casewhere an Si source other than the DCS gas is used as the precursor gas,or in the case where a C source other than the C₃H₆ gas is used as theC-containing gas, or in the case where an N source other than the NH₃gas is used as the N-containing gas. Further, the effects mentionedabove can be similarly achieved in the case where an etchant other thanthe HF gas is used as the etching gas.

(5) Exemplary Modifications

The sequence of the film forming process of the present embodiment isnot limited to the one illustrated in FIG. 4 but may be modified as inmodifications described below.

(Modification 1)

At the pre-processing step, an SiN layer not containing O and C(hereinafter, referred to as an “SiN layer not containing O” or simplyan “SiN layer”) may be formed as a seed layer.

For example, as illustrated in FIG. 5, it is possible to form the SiNlayer not containing O as a seed layer by implementing, a predeterminednumber of times (m times), a cycle which non-simultaneously(alternately) performs a step of supplying a DCS gas to the wafer 200and a step of supplying a plasma-excited NH₃ gas (NH₃*gas) to the wafer200. As mentioned above, during the step of supplying the DCS gas, Ocontained in the SiO film may be spread to the layer formed on the SiOfilm. By supplying the plasma-excited NH₃ gas to the layer containing O,O can be desorbed from the layer. As a result, it is possible to formthe SiN layer not containing O on the SiO film. The film formingsequence of this modification may be denoted as follows.

(DCS→NH₃*)×m→(DCS→C₃H₆→NH₃)×n⇒C-containing SiN film/SiN layer

Furthermore, for example, as illustrated in FIG. 6, it is possible toform an SiN layer not containing O as a seed layer by implementing, apredetermined number of times (m times), a cycle whichnon-simultaneously (alternately) performs a step of supplying a DCS gasto the wafer 200 and a step of supplying an NH₃ gas to the wafer 200,and subsequently performing a step of supplying a plasma-excited NH₃ gasto the wafer 200. The film forming sequence of this modification may bedenoted as follows.

[(DCS→NH₃)×m→NH₃*]→(DCS→C₃H₆→NH₃)×n⇒C-containing SiN film/SiN layer

In addition, for example, it is possible to form an SiN layer notcontaining O as a seed layer by implementing, a predetermined number oftimes (m₂ times), a cycle which non-simultaneously (alternately)performs a step of performing, a predetermined number of times (m₁times), a set which non-simultaneously (alternately) performs a substepof supplying a DCS gas to the wafer 200 and a substep of supplying anNH₃ gas to the wafer 200, and a step of supplying a plasma-excited NH₃gas to the wafer 200. The film forming sequence of this modification maybe illustrated as follows.

[(DCS→NH₃)×m ₁→NH₃ *]×m ₂→(DCS→C₃H₆→NH₃)×n⇒C-containing SiN film/SiNlayer

In the case where the plasma-excited NH₃ gas is supplied to the wafer200, the supply flow rate of the NH₃ gas controlled by the MFC 241 b isset at a flow rate which falls within a range of, for example, 100 to10,000 sccm. The high-frequency power applied between the rod-shapedelectrodes 269 and 270 is set at electric power which falls within arange of, for example, 50 to 1,000 W. The internal pressure of theprocess chamber 201 is set at a pressure which falls within a range of,for example, 1 to 100 Pa. The time period during which active speciesobtained by plasma-exciting the NH₃ gas are supplied to the wafer 200,namely the gas supply time period (irradiation time period), is set at atime period which falls within a range of, for example, 1 to 120seconds, specifically 1 to 60 seconds.

FIG. 10 illustrates a cross sectional structure of a film formed on thewafer 200 according to the film forming sequence of this modification.Even in this modification, the same effects as those of the film formingsequence illustrated in FIG. 4 may be achieved. That is to say, byallowing the SiN layer (the seed layer) not containing O formed at thepre-processing step to function as a block layer to suppress thespreading of O from the SiO film, it is possible to suppress theaddition of O to the C-containing SiN film. This makes it possible toenhance film characteristics of the C-containing SiN film. In addition,since the seed layer is a layer not containing O, O may not be spread tothe C-containing SiN film from the seed layer. This makes it possible tomore reliably suppress the addition of O to the C-containing SiN film.

(Modification 2)

At the pre-processing step, the surface of the SiO film may be modifiedby supplying a modification gas to the wafer 200.

For example, as illustrated in FIG. 7, by supplying a plasma-excitedN-containing gas as the modification gas to the wafer 200, it ispossible to appropriately modify the surface of the SiO film and to forma surface-modified layer on the surface of the SiO film. As theN-containing gas, it may be possible to use at least one selected from agroup consisting of an NH₃ gas and an N₂H₄ gas.

Furthermore, for example, by supplying a plasma-excited inert gas as themodification gas to the wafer 200, it is possible to appropriatelymodify the surface of the SiO film and to form a surface-modified layeron the surface of the SiO film. As the inert gas, it may be possible touse, in addition to the N₂ gas, at least one selected from a groupconsisting of an Ar gas, a He gas, a Ne gas, and a Xe gas.

Moreover, for example, by supplying a plasma-excited H-containing gas asthe modification gas to the wafer 200, it is possible to appropriatelymodify the surface of the SiO film and to form a surface-modified layeron the surface of the SiO film. As the H-containing gas, it may bepossible to use at least one selected from a group consisting of an H₂gas and a D₂ gas.

Further, for example, by supplying a plasma-excited O-containing gas asthe modification gas to the wafer 200, it is possible to appropriatelymodify the surface of the SiO film and to form a surface-modified layeron the surface of the SiO film. As the O-containing gas, it may bepossible to use, for example, an O₂ gas. In addition, for example, bysupplying an O₃ gas or an O₂+H_(z) gas as the modification gas to thewafer 200, it is also possible to appropriately modify the surface ofthe SiO film and to form a surface-modified layer on the surface of theSiO film.

By modifying the surface of the SiO film, it becomes possible to removean impurity from the surface of the SiO film and to increase purity ofthe surface of the SiO film. It also becomes possible to remove a defectfrom the surface of the SiO film. It also becomes possible to firmlybond elements constituting the SiO film on the surface of the SiO filmand to increase film density. This makes it possible to suppress theaddition of O to the C-containing SiN film by allowing thesurface-modified layer formed at the pre-processing step to act as ablock layer to suppress the spreading of O from the SiO film. As aresult, when the C-containing SiN film is formed on the SiO film, itbecomes possible to avoid generation of a pin hole in the C-containingSiN film. Furthermore, at the pre-processing step, by supplying theplasma-excited N-containing gas to the wafer 200, it become possible toplasma-nitride the surface of the SiO film and to form an SiN layer notcontaining O on the surface of the SiO film, thus further increasing theblock effects mentioned above. Moreover, at the pre-processing step, bysupplying the plasma-excited O-containing gas to the wafer 200, itbecomes possible to oxidize the surface of the SiO film and to furtherincrease the modification effects mentioned above.

FIG. 11 illustrates a cross sectional structure of a film formed on thewafer 200 according to the film forming sequence of this modification.Even in this modification, the same effects as those of the film formingsequence illustrated in FIG. 4 may be achieved.

In the case where the plasma-excited modification gas is supplied to thewafer 200, the supply flow rate of the modification gas controlled bythe MFC 241 b is set at a flow rate which falls within a range of, forexample, 100 to 10,000 sccm. The high-frequency power applied betweenthe rod-shaped electrodes 269 and 270 is set at electric power whichfalls within a range of, for example, 50 to 1,000 W. The internalpressure of the process chamber 201 is set at a pressure which fallswithin a range of, for example, 1 to 100 Pa. The time duration duringwhich active species obtained by plasma-exciting the modification gas issupplied to the wafer 200, namely the gas supply time (irradiationtime), is set at a time period which falls within a range of, forexample, 10 to 600 seconds, specifically 30 to 300 seconds.

(Modification 3)

At the pre-processing step or the protective film forming step, a cyclewhich non-simultaneously performs a step of supplying a precursor gas tothe wafer 200 and a step of supplying a gas containing C and N to thewafer 200 may be implemented a predetermined number of times (n times).As the precursor gas, it may be possible to use, for example, achlorosilane precursor gas such as an HCDS gas. As the gas containing Cand N, it may be possible to use, for example, an amine-based gas suchas a triethylamine ((C₂H₅)₃N: abbreviation: TEA) gas. In this case, theSiN layer containing O and C is formed as a seed layer. The supplyconditions of the gas containing C and N may be similar to, for example,those of the N-containing gas at step 3 p of the film forming sequenceillustrated in FIG. 4. The film forming sequence of this modificationmay be illustrated as follows.

(HCDS→TEA)×m→(HCDS→TEA)×n⇒C-containing SiN film/SiN layer containing Oand C

Furthermore, at the pre-processing step or the protective film formingstep, a cycle which non-simultaneously performs a step of supplying aprecursor gas containing C to the wafer 200 and a step of supplying anN-containing gas to the wafer 200 may be implemented a predeterminednumber of times (n times). As the precursor gas containing C, it may bepossible to use, for example, an alkylhalosilane precursor gas such as a1,1,2,2-tetrachloro-1,2-dimethylsilane ((CH₃)₂Si₂Cl₄, abbreviation:TCDMDS) gas or an alkylenehalosilane precursor gas such as abis(trichlorosilyl) methane ((SiCl₃)₂CH₂, abbreviation: BTCSM) gas. Anyprecursor is a precursor including Si—C bonds and acts as an Si sourceand a C source. In this case, the SiN layer containing O and C is formedas a seed layer. The supply conditions of the precursor gas containing Cmay be similar to, for example, those of the precursor gas at step 1 pof the film forming sequence illustrated in FIG. 4. The film formingsequence of this modification may be illustrated as follows.

(TCDMDS→NH₃)×m→(TCDMDS→NH₃)×n⇒C-containing SiN film/SiN layer containingO and C

Even in this modification, the same effects as those of the film formingsequence illustrated in FIG. 4 may be achieved.

(Modification 4)

The C-containing SiN film as a protective film may be directly formed onthe surface of the SiO film, without performing the pre-processing step.Even in this modification, the same effects as those of the film formingsequence illustrated in FIG. 4 may be achieved. That is to say, byadding C to the SiN film, it becomes possible to form the SiN film as apin hole-free film even when the protective film is thinned.

(Modification 5)

After the C-containing SiN film is formed, a cap layer may be formed onthe surface of the C-containing SiN film within the same process chamber201, namely, in-situ.

For example, as illustrated in FIG. 8, by modifying the surface of theC-containing SiN film by supplying a plasma-excited N-containing gas asa modification gas to the wafer 200 on which the C-containing SiN filmis formed, it is possible to form an SiN layer as the cap layer on thesurface of the C-containing SiN film. The process procedures and processconditions at this time may be similar to those illustrated inmodification 2. Furthermore, in FIG. 8, for the sake of convenience, thepre-processing step is not illustrated. The film forming sequence ofthis modification may be illustrated as follows. As the N-containinggas, it may be possible to use, in addition to the NH₃ gas, an N₂H₄ gas,an N₂H₄ gas, and an N₃H₈ gas.

(DCS→C₃H₆→NH₃)×m→(DCS→C₃H₆→NH₃)×n→NH₃*⇒SiN layer/C-containing SiNfilm/SiN layer containing O and C

FIG. 12 illustrates a cross sectional structure of a film formed on thewafer 200 according to the film forming sequence of this modification.Even in this modification, the same effects as those of the film formingsequence illustrated in FIG. 4 may be achieved. Furthermore, by formingthe cap layer (SiN layer) on the surface of the C-containing SiN film,when the wafer 200 on which the C-containing SiN film is formed istransferred in the air, it is possible to suppress the oxidation of theC-containing SiN film due to water vapor (H₂O) in the air. In addition,after the C-containing SiN film is formed, by forming a cap layer in astate where the wafer 200 which has been subjected to the film formingprocess is accommodated in the process chamber 201, without unloadingfrom the interior of the process chamber 201, it becomes possible tomore reliably suppress the oxidation of the C-containing SiN film.

It is also possible to form the cap layer under the same processprocedures as those of the pre-processing step illustrated inmodification 1, in addition to the aforementioned process procedures.The film forming sequence of this modification may be illustrated asfollows.

(DCS→C₃H₆→NH₃)×m ₁→(DCS→C₃H₆→NH₃)×n→(DCS→NH₃*)×m ₂⇒SiNlayer/C-containing SiN film/SiN layer containing O and C

(DCS→C₃H₆→NH₃)×m ₁→(DCS→C₃H₆→NH₃)×n→[(DCS→NH₃)×m ₂→NH₃]⇒SiNlayer/C-containing SiN film/SiN layer containing O and C

(DCS→C₃H₆→NH₃)×m ₁→(DCS→C₃H₆→NH₃)×n→[(DCS→NH₃)×m ₂→NH₃ ]×m ₃⇒SiNlayer/C-containing SiN film/SiN layer containing O and C

Second Embodiment

A second embodiment of the present disclosure will now be mainlydescribed with reference to FIGS. 13A to 13C.

This embodiment is different from the aforementioned embodiment, in thata concave portion is formed on a surface of the wafer 200 and the wafer200 in which an oxide film such as an SiO film or the like is formed onan inner surface of the concave portion is processed. At apre-processing step, an SiN layer containing O and C is formed as a seedlayer on the inner surface of the concave portion in which the SiO filmis formed. Furthermore, at a protective film forming step, an SiN filmcontaining C as a protective film is formed to fill the interior of theconcave portion in which the seed layer is formed. Thereafter, the wafer200 is subjected to a heating process under a temperature conditionhigher than a temperature of the wafer 200 at the protective filmforming step. Hereinafter, the second embodiment will be described indetail with a focus on differences from the aforementioned embodiment.

FIG. 13A illustrates a cross sectional structure of the wafer 200 beforethe film forming process. For example, a concave portion having, forexample, a cylinder structure, a trench structure or the like is formedon the surface of the wafer 200. For example, an aspect ratio of theconcave portion, namely a ratio of a depth to an inner diameter of theconcave portion (depth/inner diameter) is about 5 to 100. Furthermore,an SiO film is formed on the surface of the wafer 200 including theinner surface of the concave portion. The SiO film may be a film to beprotected by the C-containing SiN film, at an etching process which willbe performed later.

A seed layer (SiN layer containing O and C) and a protective film(C-containing SiN film) are sequentially formed on the SiO film of thewafer 200 configured as described above. For example, the formation ofthe seed layer and the protective film may be performed using thesubstrate-processing apparatus illustrated in FIG. 1 and under the sameprocedures and process conditions as those of the film forming sequenceillustrated in FIG. 4 or as those of the respective modificationsdescribed above. Even in this embodiment, similar to the aforementionedembodiment, the pre-processing step may be omitted.

FIG. 13B illustrates a cross sectional structure of the wafer 200 afterthe formation of the C-containing SiN film. The C-containing SiN film isformed to fill the interior of the concave portion while continuouslycovering the surface of the SiO film. As mentioned above, since thesupply of the DCS gas to the wafer 200, the supply of the C₃H₆ gas tothe wafer 200, and the supply of the NH₃ gas to the wafer 200 arenon-simultaneously performed in the film forming process, it is possibleto form the C-containing SiN film within the concave portion with goodstep coatability.

However, at this stage, an interface structure extending in a depthdirection may be often present within the concave portion. That is tosay, the C-containing SiN films grown from facing surfaces of the innerwalls of the concave portion are close to or make contact with eachother in the respective surfaces, but at least a portion of therespective surfaces may not join each other. Hereinafter, thenon-junction portion of the C-containing SiN film within the concaveportion may be referred to as a “joint interface”. In the case where theconcave portion has a cylinder structure, a joint interface formedwithin the concave portion may have, for example, a fine hole shapeextending in a depth direction of the concave portion. Furthermore, inthe case where the concave portion has a trench structure, a jointinterface formed within the concave portion may have, for example, acrevasse shape extending in a depth direction of the concave portion.The joint interface may act as a path through which an etchant enterstoward the SiO film side, i.e., as a pin hole, in the subsequent etchingprocess. The joint interface is easily generated as the aspect ratio ofthe concave portion is increased, specifically, 5 or more, for example,20 or more, ultimately 50 or more.

Thus, in this embodiment, in order to eliminate the joint interface, thewafer 200 on which the C-containing SiN film is formed is subjected tothe heating process (annealing process). The heating process isperformed under a temperature condition higher than the temperature ofthe wafer 200 at the protective film forming step. The heating processmay be performed using the substrate-processing apparatus illustrated inFIG. 1.

Specifically, after the C-containing SiN film is formed on the wafer200, the interior of the process chamber 201 is exhausted by the sameprocess procedures as those of the purge step of the aforementionedembodiment. Then, an N₂ gas, which is an inert gas serving as anannealing gas, is supplied into the process chamber 201, and theinterior of the process chamber 201 is substituted with an atmosphere ofthe N₂ gas. At this time, the N₂ gas is supplied using at least one orboth of the gas supply pipes 232 d and 232 e. Then, the APC valve 244 iscontrolled such that the interior of the process chamber 201 has adesired process pressure. Furthermore, the heater 207 is controlled suchthat the temperature (heating process temperature) of the wafer 200becomes a predetermined process temperature higher than the temperature(film formation temperature) of the wafer 200 at the protective filmforming step. The interior of the process chamber 201 is substitutedwith the N₂ gas atmosphere having a desired process pressure and thetemperature of the wafer 200 becomes equal to the desired processtemperature. This state is maintained for a predetermined period oftime. Furthermore, in the case where the heating process temperature isset at a temperature lower than the film formation temperature, forexample, 300 to 650 degrees C., it may be difficult for C to be desorbedfrom the C-containing SiN film. This makes it difficult to eliminate thejoint interface formed within the concave portion for the reasondescribed later.

The process conditions of the heating process are illustrated asfollows.

Heating process temperature: 700 to 800 degrees C.

Process pressure: atmospheric pressure

Flow rate of the annealing gas (N₂ gas): 100 to 10,000 sccm

Process time: 30 to 180 min.

By performing the heating process under the aforementioned conditions,it becomes possible to unite the C-containing SiN films formed withinthe concave portion and to eliminate the joint interface, as illustratedin FIG. 13C. That is to say, it becomes possible to integrally join thesurfaces of the C-containing SiN films grown from the mutually facingsurfaces of the inner walls of the concave portion with no gap. As aresult, the interior of the concave portion is uniformly embedded by theC-containing SiN film. Furthermore, the aforementioned joiningappropriately uses a phenomenon that C is desorbed from the surface ofthe C-containing SiN film through the heating process. The reason isbecause, when C is desorbed from the surface of the C-containing SiNfilm by performing the heating process, Si which was bonded to C has adangling bond. Further, the aforementioned joining is promoted as Sihaving the dangling bond and another Si having the dangling bond arebonded (by forming an Si—Si bond). In this regard, in the case where aprotective film is formed of an SiN film not containing C, it isimpossible to use the desorption reaction of C described above.Accordingly, it is difficult to eliminate the joint interface eventhough the process temperature is set at a temperature higher than theaforementioned temperature range.

As the annealing gas, it may be possible to use, in addition to the N₂gas, a rare gas such as an Ar gas, a He gas, a Ne gas, a Xe gas or thelike, or an H₂ gas. As the annealing gas, it also may be possible to usean O-containing gas such as an O₂ gas. In these cases, the annealing gasmay be supplied from any of the gas supply pipes 232 a to 232 e. Theprocess conditions may be similar to the aforementioned conditions.

Furthermore, in the case of using an O-containing gas as the annealinggas, a gaseous substance such as, for example, CO₂ or the like isgenerated due to a reaction between C contained in the C-containing SiNfilm and the O-containing gas, making it possible to promote thedesorption of C from the C-containing SiN film. As a result, it becomespossible to finely adjust a concentration of C in the C-containing SiNfilm. Moreover, by desorbing C from the C-containing SiN film, itbecomes possible to reliably eliminate the joint interface formed withinthe concave portion. As the O-containing gas, it may be possible to use,in addition to the O₂ gas, a nitrous oxide (N₂O) gas, a nitrogenmonoxide (NO) gas, a nitrogen dioxide (NO₂) gas, an O₃ gas, an H₂ gas+O₂gas, an H₂ gas+O₃ gas, water vapor (H₂O gas), a carbon monoxide (CO)gas, a carbon dioxide (CO₂) gas or the like.

When the joint interface is eliminated, the wafer 200 which has beensubjected to the heating process is unloaded from the interior of theprocess chamber 201. Then, similar to the aforementioned embodiment, anadditional film forming process, additional resist pattern formingprocess and the like are performed on the wafer 200 which has beensubjected to the heating process. Then, the etching process is performedon the thin film or the like formed on the surface of the wafer 200according to the same process procedures and process conditions as thoseof the aforementioned embodiment. At this time, the C-containing SiNfilm, which has been subjected to the heating process, formed on thewafer 200, functions as a protective film to protect the underlying SiOfilm.

Even in this embodiment, the same effects as those of the aforementionedembodiment may be achieved. Furthermore, in the case where the concaveportion of the surface of the wafer 200 is embedded by the protectivefilm, the joint interface generated in the protective film can beeliminated by the heating process. In particular, by forming theC-containing SiN film as a protective film, it becomes possible to morereliably eliminate the joint interface. Accordingly, it becomes possibleto form a protective film with a smooth surface. In addition, byeliminating the joint interface, it becomes possible to suppress anetchant from reaching an underlying film through the joint interfacewhen performing the etching process, and to more reliably reduce anetching damage to the underlying film. Moreover, it becomes possible toprevent an etchant from entering the joint interface and to furthersuppress the etching of the protective film itself. Thus, it is possibleto more reliably avoid a degradation of the function as the protectivefilm. Furthermore, it was confirmed that the same effects as theaforementioned effects based on the heating process may be achieved evenwhen an aspect ratio of the concave portion is 5 or more, for example,20 or more, ultimately 50 or more. As mentioned above, the jointinterface is easily generated as the aspect ratio of the concave portionis increased. Thus, the heating process of this embodiment is meaningfulparticularly when the concave portion having such a high aspect ratio asdescribed above is embedded by the protective film.

OTHER EMBODIMENTS

While some embodiments of the present disclosure have been specificallydescribed above, the present disclosure is not limited to theaforementioned embodiments but may be differently modified withoutdeparting from the spirit of the present disclosure.

For example, in the aforementioned embodiments, the process proceduresand the process conditions are the same at the pre-processing step andthe protective film forming step, except for the number of times ofperforming a cycle, but these may be different. For example, at thepre-processing step and the protective film forming step, the order ofsupplying gases may be different. Furthermore, for example, at thepre-processing step and the protective film forming step, the type ofthe precursor gas may be different, the type of the C-containing gas maybe different, or the type of the N-containing gas may be different. Inaddition, for example, at the pre-processing step and the protectivefilm forming step, the process conditions such as the temperature of thewafer 200, the internal pressure of the process chamber 201, and thesupply flow rate or the supply time of each gas may be different.

Moreover, for example, the C-containing SiN film formed as a protectivefilm may be a film further containing at least one of O and boron (B).That is to say, either the C-containing SiON film or C-containing SiBNfilm, rather than the C-containing SiN film, may be formed as aprotective film. In other words, a film may further contain O or B aslong as it contains three elements of Si, C, and N as a protective film.Also, a laminated film obtained by laminating two or more types of theC-containing SiN film, the C-containing SiON film, and the C-containingSiBN film in any combination may be formed as a protective film. TheC-containing SiON film may also be referred to as an SiN film containingC and O, and the C-containing SiBN film may also be referred to as anSiN film containing C and B.

In order to form the C-containing SiON film, when performing theaforementioned cycle, a step of supplying, for example, an O₂ gas as anO-containing gas into the process chamber 201 may be performednon-simultaneously with steps 1 to 3. The O₂ gas may be supplied fromthe gas supply pipe 232 b. The supply flow rate of the O₂ gas controlledby the MFC 241 b may be set at a flow rate which falls within a rangeof, for example, 100 to 10,000 sccm. Other process procedures andprocess conditions may be similar to, for example, those of the filmforming sequence described above with reference to FIG. 4. As theO-containing gas, for example, it may be possible to use, in addition tothe O₂ gas, an N₂O gas, an NO gas, an NO₂ gas, an O₃ gas, an H₂ gas+O₂gas, an H₂ gas+O₃ gas, an H₂O gas, a CO gas, a CO₂ gas or the like.

In order to form the C-containing SiBN film, when performing theaforementioned cycle, a step of supplying, for example, atrichloroborane (BCl₃) gas as a B-containing gas into the processchamber 201 may be performed non-simultaneously with steps 1 to 3. TheBCl₃ gas may be supplied from the gas supply pipe 232 b. The supply flowrate of the BCl₃ gas controlled by the MFC 241 b may be set at a flowrate which falls within a range of, for example, 100 to 10,000 sccm.Other process procedures and process conditions may be similar to, forexample, those of the film forming sequence described above withreference to FIG. 4. As the B-containing gas, it may be possible to use,in addition to the BCl₃ gas, a monochloroborane (BClH₂) gas, adichloroborane (BCl₂H) gas, a trifluoroborane (BF₃) gas, atribromoborane (BBr₃) gas, a diborane (B₂H₆) gas or the like.

The present disclosure may be appropriately applied to a case where anitride film containing C and a metal element such as titanium (Ti),zirconium (Zr), hafnium (Hf), taltanum (Ta), niobium (Nb), molybdenum(Mo), tungsten (W), yttrium (Y), strontium (Sr), aluminum (Al) or thelike, namely a metal nitride film containing C, are formed on the wafer200. That is to say, the present disclosure may be applied to a casewhere, for example, a TiN film containing C, a ZrN film containing C, anHfN film containing C, a TaN film containing C, a NbN film containing C,a MoN film containing C, a WN film containing C, a YN film containing C,an SrN film containing C, or an AN film containing C is formed on thewafer 200.

For example, the present disclosure may be appropriately applied to acase where a metal compound gas (metal precursor) containing theaforementioned metal elements is used as a precursor, and a seed layer(a metal nitride layer containing O and C) and a C-containing metalnitride film are sequentially formed on an oxide film formed on thesurface of the wafer 200 according to a film forming sequenceillustrated later.

(Metal precursor→C₃H₆→NH₃)×m→(Metal precursor→C₃H₆→NH₃)×n⇒C-containingmetal nitride film/metal nitride layer containing O and C

(Metal precursor→NH3*)×m→(Metal precursor→C₃H₆→NH₃)×n⇒C-containing metalnitride film/metal nitride layer

[(Metal precursor→NH₃)×m→NH₃*](→Metal precursor→C₃H₆→NH₃)×n⇒C-containingmetal nitride film/metal nitride layer

[(Metal precursor→NH₃)×m ₁→NH₃ *]×m ₂→(Metalprecursor→C₃H₆→NH₃)×n⇒C-containing metal nitride film/metal nitridelayer

Furthermore, similar to the aforementioned modifications, a cap layer(metal nitride layer) may be formed on the surface of the C-containingmetal nitride film.

That is to say, the present disclosure may be appropriately applied to acase where a C-containing semiconductor nitride film or a C-containingmetal nitride film is formed. Process procedures and process conditionsof this film forming process may be similar to the process proceduresand process conditions of the embodiments or the modifications describedabove. Even in this case, the same effects as those of the embodimentsor the modifications described above may be achieved.

Recipes (programs describing process procedures and process conditions)used in substrate process may be prepared individually according toprocessing contents (the kind, composition ratio, quality, filmthickness, process procedure and process condition of a film to beformed) and may be stored in the memory device 121 c via atelecommunication line or the external memory device 123. Moreover, atthe start of the substrate process, the CPU 121 a may properly select anappropriate recipe from the recipes stored in the memory device 121 caccording to the processing contents. Thus, it is possible for a singlesubstrate-processing apparatus to form films of different kinds,composition ratios, qualities and thicknesses with enhancedreproducibility. In addition, it is possible to reduce an operator'sburden (e.g., a burden borne by an operator when inputting processprocedures and process conditions) and to quickly start the substrateprocess while avoiding an operation error.

The recipes mentioned above are not limited to newly-prepared ones butmay be prepared by, for example, modifying the existing recipes alreadyinstalled in the substrate-processing apparatus. When modifying therecipes, the modified recipes may be installed in thesubstrate-processing apparatus via a telecommunication line or arecording medium storing the recipes. In addition, the existing recipesalready installed in the substrate-processing apparatus may be directlymodified by operating the input/output device 122 of the existingsubstrate-processing apparatus.

In the aforementioned embodiments, there has been described an examplein which films are formed using a batch-type substrate-processingapparatus capable of processing a plurality of substrates at a time. Thepresent disclosure is not limited to the aforementioned embodiment butmay be appropriately applied to, e.g., a case where films are formedusing a single-wafer-type substrate-processing apparatus capable ofprocessing a single substrate or several substrates at a time. Inaddition, in the aforementioned embodiments, there has been described anexample in which films are formed using a substrate-processing apparatusprovided with a hot-wall-type process furnace. The present disclosure isnot limited to the aforementioned embodiments but may be appropriatelyapplied to a case where films are formed using a substrate-processingapparatus provided with a cold-wall-type process furnace. Even in thesecases, process procedures and the process conditions may be similar to,for example, the process procedures and the process conditions of theaforementioned embodiments.

The present disclosure may be suitably applied to, e.g., a case wherefilms are formed using a substrate-processing apparatus provided with aprocess furnace 302 illustrated in FIG. 15. The process furnace 302includes a process vessel 303 which defines a process chamber 301, ashower head 303 s as a gas supply part configured to supply a gas intothe process chamber 301 in a shower-like manner, a support table 317configured to horizontally support one or more wafers 200, a rotaryshaft 355 configured to support the support table 317 from below, and aheater 307 installed in the support table 317. Gas supply ports 332 aand 332 b are connected to inlets (gas introduction holes) of the showerhead 303 s. A gas supply system similar to the first supply system ofthe aforementioned embodiment is connected to the gas supply port 332 a.A remote plasma unit (plasma generation device) 339 b as an excitationpart for plasma-exciting and supplying a gas and a gas supply systemsimilar to the second and third supply systems of the aforementionedembodiment are connected to the gas supply port 332 b. A gasdistribution plate configured to supply a gas into the process chamber301 in a shower-like manner is installed in outlets (gas dischargeholes) of the shower head 303 s. The shower head 303 s is installed atsuch a position as to face the surfaces of the wafers 200 carried intothe process chamber 301. An exhaust port 331 configured to exhaust theinterior of the process chamber 301 is installed in the process vessel303. An exhaust system similar to the exhaust system of theaforementioned embodiment is connected to the exhaust port 331.

In addition, the present disclosure may be suitably applied to, e.g., acase where films are formed using a substrate-processing apparatusprovided with a process furnace 402 illustrated in FIG. 16. The processfurnace 402 includes a process vessel 403 which defines a processchamber 401, a support table 417 configured to horizontally support oneor more wafers 200, a rotary shaft 455 configured to support the supporttable 417 from below, a lamp heater 407 configured to irradiate lighttoward the wafers 200 disposed in the process vessel 403, and a quartzwindow 403 w which transmits the light irradiated from the lamp heater407. Gas supply ports 432 a and 432 b are connected to the processvessel 403. A supply system similar to the first supply system of theaforementioned embodiment is connected to the gas supply port 432 a. Theaforementioned remote plasma unit 339 b and a supply system similar tothe second and third supply systems of the aforementioned embodiment areconnected to the gas supply port 432 b. The gas supply ports 432 a and432 b are respectively installed at the lateral side of the end portionsof the wafers 200 carried into the process chamber 401, namely at suchpositions as not to face the surfaces of the wafers 200 carried into theprocess chamber 401. An exhaust port 431 configured to exhaust theinterior of the process chamber 401 is installed in the process vessel403. An exhaust system similar to the exhaust system of theaforementioned embodiment is connected to the exhaust port 431.

The aforementioned annealing process may be performed using a firstsubstrate processing part for performing the film forming process or asecond substrate processing part for performing the etching process, orusing a third substrate processing part, namely a dedicated annealingdevice different from the first and second substrate processing parts.Furthermore, such substrate processing parts are not limited to a caseof being configured as a dependent device (stand-alone type device)group but may also be configured as a single device (cluster typedevice) mounted on the same platform.

Even in the case of using the aforementioned substrate-processingapparatuses, the film forming process may be performed in the sameprocess procedures and process conditions as those of the embodimentsand modifications described above. Thus, the same effects as those ofthe embodiments and modifications described above may be achieved.

The embodiments and modifications described above may be appropriatelycombined with one another. Process procedures and process conditionsused at this time may be similar to, for example, the process proceduresand process conditions of the aforementioned embodiment.

Examples

In an example, the substrate-processing apparatus of the aforementionedembodiments was used and a seed layer (an SiN layer containing O and C)and a protective film (C-containing SiN film) were sequentially formedon a wafer on which an SiO film having a film thickness of about 1,000 Åis formed on a surface of the wafer according to the film formingsequence illustrated in FIG. 4. A DCS gas was used as a precursor gas,an NH₃ gas was used as an N-containing gas, and a C₃H₆ gas was used as aC-containing gas. As the process conditions, conditions within theprocess conditions described in the aforementioned embodiments wereused. Furthermore, before performing the film forming process, a filmthickness A of the SiO film was measured in advance from 49 placesin-plane of the wafer. In addition, after the protective film wasformed, a film thickness B of a laminated film in which the SiO film,the seed layer, and the protective film were laminated (hereinafter,also referred to as a laminated film in which the SiO film and theprotective film are laminated for the sake of convenience) was measured.Measurement points of the film thickness B were identical to those ofthe film thickness A. In addition, about 30 Å of a difference betweenthe film thickness A and the film thickness B is a thickness of the sumof the seed layer and the protective film.

Further, in a comparative example, the substrate-processing apparatus ofthe aforementioned embodiments was used, and an SiN film not containingC was formed as a protective film on a wafer on which an SiO film havinga film thickness of about 1,000 Å is formed. The formation of the SiNfilm was performed according to a film forming sequence of implementing,a predetermined number of times, a cycle of non-simultaneouslyperforming a step of supplying a precursor gas to the wafer in theprocess chamber and a step of supplying an N-containing gas to the waferin the process chamber. A DCS gas was used as a precursor gas and an NH₃gas was used as an N-containing gas. As the process conditions,conditions within the process conditions described in the aforementionedembodiments were used. Furthermore, before performing the film formingprocess, like the above Example, a film thickness A of the SiO film wasmeasured in advance from 49 places in-plane of the wafer. Further, afterthe protective film was formed, similar to the above Example, a filmthickness B of a laminated film in which the seed layer and theprotective film were laminated was measured. Measurement points of thefilm thickness B were similar to those of the film thickness A. Inaddition, about 30 Å of a difference between the film thickness A andthe film thickness B is a thickness of the sum of the seed layer and theprotective film.

Furthermore, regarding respective samples of the above Example and thecomparative example, an etching process of supplying a 1% of HF solutionon the surface of the wafer was performed. Thereafter, regarding therespective samples of the above Example and the comparative example,film thicknesses B′ of the laminated films in which the SiO film and theprotective film were laminated were measured. Measurement points of thefilm thickness B′ were similar to those of the film thicknesses A and B.

FIG. 14A is a diagram illustrating an evaluation result of etchingtolerance of a protective film in the above Example and FIG. 14B adiagram illustrating an evaluation result of etching tolerance of aprotective film in the comparative example. In either of the drawings,the vertical axis represents a film thickness [Å] and the horizontalaxis represents measurement places of a film thickness. Further, in thedrawings, the solid lines represent a film thickness A of the SiO filmand the two point chain lines represent a film thickness B of alaminated film before the etching process is performed, and the dottedlines represent a film thickness B′ of the laminated film after theetching process is performed.

As illustrated in FIG. 14A, it can be seen that, in the above Example,the film thickness of the laminated film is not mostly changed beforeand after the etching process. Specifically, it can be seen that anetched amount of the C-containing SiN film constituting a protectivefilm is less than 2 Å over the entire surface of the wafer and theunderlying SiO film is protected without being etched over the entiresurface of the wafer. In contrast, as illustrated in FIG. 14B, in thecomparative example, it can be seen that the film thickness of thelaminated film is significantly changed before and after the etchingprocess. Specifically, it can be seen that the SiN film not containing Cconstituting a protective film is etched and mostly eliminated over theentire surface of the wafer, and the underlying SiO film is partiallyetched to reduce the film thickness.

In this sense, it can be seen that, by forming the SiN layer containingO and C as a seed layer before the formation of a protective film andadding C to the SiN film constituting the protective film, it ispossible to suppress the degradation of a function as the protectivelayer and to sufficiently protect the underlying SiO film. In addition,it can be seen that, by setting a film thickness of the C-containing SiNfilm to become 2 Å or more, it is possible to sufficiently protect theunderlying SiO film. Moreover, it can be seen that, by setting a filmthickness of the C-containing SiN film to become 5 Å or more,specifically 10 Å or more, it is possible to reliably protect theunderlying SiO film even when there is a variation in the etched amountof the C-containing SiN film. Further, the present inventors confirmedthat, by setting a film thickness of the C-containing SiN film to become20 Å or more, specifically 30 Å or more, it is possible to furtherincrease the number of Si—C bonds included in the film, to furtherenhance the function of the film as the protective film, and to morereliably protect the underlying SiO film.

What is claimed is:
 1. A method for manufacturing a semiconductordevice, comprising: preparing a substrate with an oxide film formed on asurface of the substrate; performing a pre-processing to form a nitridelayer containing oxygen and carbon on a surface of the oxide film byusing the oxide film as an oxygen source, and by performing a cycle apredetermined number of times, the cycle including non-simultaneouslyperforming: supplying a precursor gas to the substrate; supplying acarbon-containing gas to the substrate; and supplying anitrogen-containing gas to the substrate, or by performing a cycle apredetermined number of times, the cycle including non-simultaneouslyperforming: supplying a precursor gas to the substrate; and supplying agas containing carbon and nitrogen to the substrate, or by performing acycle a predetermined number of times, the cycle includingnon-simultaneously performing: supplying a precursor gas containingcarbon to the substrate; and supplying a nitrogen-containing gas to thesubstrate; and forming a nitride film containing carbon on the surfaceof the oxide film on which the pre-processing has been performed, byperforming a cycle a predetermined number of times, the cycle includingnon-simultaneously performing: supplying a precursor gas to thesubstrate; supplying a carbon-containing gas to the substrate; andsupplying a nitrogen-containing gas to the substrate, or by performing acycle a predetermined number of times, the cycle includingnon-simultaneously performing: supplying a precursor gas to thesubstrate; and supplying a gas containing carbon and nitrogen to thesubstrate, or by performing a cycle a predetermined number of times, thecycle including non-simultaneously performing: supplying a precursor gascontaining carbon to the substrate; and supplying a nitrogen-containinggas to the substrate.
 2. The method of claim 1, wherein the act ofperforming the pre-processing and the act of forming the nitride filmcontaining carbon are performed in a state where the substrate isaccommodated in a process chamber, and wherein the method furthercomprises forming a cap layer on a surface of the nitride filmcontaining carbon in the same process chamber, after the act of formingthe nitride film containing carbon.
 3. The method of claim 1, wherein athickness of the nitride film containing carbon is equal to or greaterthan 0.2 nm, and is equal to or smaller than 10 nm.
 4. The method ofclaim 1, wherein a concentration of carbon in the nitride filmcontaining carbon is equal to or higher than 3 atomic %, and is equal toor lower than 10 atomic %.
 5. The method of claim 1, further comprisingperforming an etching process to the substrate on which the nitride filmcontaining carbon is formed.
 6. The method of claim 1, wherein a concaveportion is formed in the surface of the substrate, and the oxide film isformed on an inner surface of the concave portion, wherein, in the actof forming the nitride film containing carbon, the nitride filmcontaining carbon is formed to fill an interior of the concave portionin which the oxide film is formed, and wherein the method furthercomprises, after the act of forming the nitride film containing carbon,heat-processing the substrate under a temperature higher than atemperature of the substrate in the act of forming the nitride filmcontaining carbon.
 7. A substrate-processing apparatus, comprising: aprocess chamber in which a substrate is processed; a supply systemconfigured to supply gases to the substrate in the process chamber; anda controller configured to control the supply system so as to: after thesubstrate with an oxide film formed on a surface of the substrate isprepared, perform a pre-processing to form a nitride layer containingoxygen and carbon on a surface of the oxide film by using the oxide filmas an oxygen source, and by performing a cycle a predetermined number oftimes, the cycle including non-simultaneously performing: supplying aprecursor gas to the substrate; supplying a carbon-containing gas to thesubstrate; and supplying a nitrogen-containing gas to the substrate, orby performing a cycle a predetermined number of times, the cycleincluding non-simultaneously performing: supplying a precursor gas tothe substrate; and supplying a gas containing carbon and nitrogen to thesubstrate, or by performing a cycle a predetermined number of times, thecycle including non-simultaneously performing: supplying a precursor gascontaining carbon to the substrate; and supplying a nitrogen-containinggas to the substrate; and form a nitride film containing carbon on thesurface of the oxide film on which the pre-processing has beenperformed, by performing a cycle a predetermined number of times, thecycle including non-simultaneously performing: supplying a precursor gasto the substrate; supplying a carbon-containing gas to the substrate;and supplying a nitrogen-containing gas to the substrate, or byperforming a cycle a predetermined number of times, the cycle includingnon-simultaneously performing: supplying a precursor gas to thesubstrate; and supplying a gas containing carbon and nitrogen to thesubstrate, or by performing a cycle a predetermined number of times, thecycle including non-simultaneously performing: supplying a precursor gascontaining carbon to the substrate; and supplying a nitrogen-containinggas to the substrate.
 8. A non-transitory computer-readable recordingmedium storing a program that causes, by a computer, a substrateprocessing apparatus to perform, in a process chamber of the substrateprocessing apparatus, a process of: preparing a substrate with an oxidefilm formed on a surface of the substrate; performing a pre-processingto form a nitride layer containing oxygen and carbon on a surface of theoxide film by using the oxide film as an oxygen source, and byperforming a cycle a predetermined number of times, the cycle includingnon-simultaneously performing: supplying a precursor gas to thesubstrate; supplying a carbon-containing gas to the substrate; andsupplying a nitrogen-containing gas to the substrate, or by performing acycle a predetermined number of times, the cycle includingnon-simultaneously performing: supplying a precursor gas to thesubstrate; and supplying a gas containing carbon and nitrogen to thesubstrate, or by performing a cycle a predetermined number of times, thecycle including non-simultaneously performing: supplying a precursor gascontaining carbon to the substrate; and supplying a nitrogen-containinggas to the substrate; and forming a nitride film containing carbon onthe surface of the oxide film on which the pre-processing has beenperformed, by performing a cycle a predetermined number of times, thecycle including non-simultaneously performing: supplying a precursor gasto the substrate; supplying a carbon-containing gas to the substrate;and supplying a nitrogen-containing gas to the substrate, or byperforming a cycle a predetermined number of times, the cycle includingnon-simultaneously performing: supplying a precursor gas to thesubstrate; and supplying a gas containing carbon and nitrogen to thesubstrate, or by performing a cycle a predetermined number of times, thecycle including non-simultaneously performing: supplying a precursor gascontaining carbon to the substrate; and supplying a nitrogen-containinggas to the substrate.